Polyaxial bone anchor with pop-on shank and friction fit retainer with low  profile edge lock

ABSTRACT

A polyaxial bone screw assembly includes a threaded shank body having an integral upper portion receivable in an integral receiver, the receiver having an upper channel for receiving a longitudinal connecting member and a lower cavity cooperating with a lower opening. A down-loadable compression insert, a down-loadable friction fit split retaining ring having inner and outer tangs and an up-loadable shank upper portion cooperate to provide for pop- or snap-on assembly of the shank with the receiver either prior to or after implantation of the shank into a vertebra. The shank and receiver once assembled cannot be disassembled.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/573,303, now U.S. Pat. No. ______, which claims the benefit of U.S.Provisional Patent Application Ser. No. 61/573,508 filed Sep. 7, 2011,each of which is incorporated by reference herein.

This application is also a continuation-in-part of U.S. patentapplication Ser. No. 13/506,365 filed Apr. 13, 2012 that claims thebenefit of U.S. Provisional Patent Application Ser. No. 61/517,088 filedApr. 13, 2011, both of which are incorporated by reference herein. Thisapplication is also a continuation-in-part of U.S. patent applicationSer. No. 13/385,212 filed Feb. 8, 2012 that claims the benefit of U.S.Provisional Patent Application Ser. No. 61/463,037 filed Feb. 11, 2011,both of which are incorporated by reference herein. This application isalso a continuation-in-part of U.S. patent application Ser. No.13/374,439 filed Dec. 29, 2011 is incorporated by reference herein. Thisapplication is also an continuation-in-part of U.S. patent applicationSer. No. 13/373,289, filed Nov. 9, 2011 that claims the benefit of U.S.Provisional Patent Application Ser. No. 61/456,649 filed Nov. 10, 2010and Provisional Patent Application Ser. No. 61/460,234 filed Dec. 29,2010, all of which are incorporated by reference herein. Thisapplication is also a continuation-in-part of U.S. patent applicationSer. No. 13/136,331 filed Jul. 28, 2011 that claims the benefit of U.S.Provisional Patent Application Ser. Nos. 61/400,504 filed Jul. 29, 2010,and 61/403,915 filed Sep. 23, 2010, all of which are incorporated byreference herein. This application is also a continuation-in-part ofU.S. patent application Ser. No. 12/924,802 filed Oct. 5, 2010 thatclaims the benefit of the following U.S. Provisional Patent ApplicationSer. Nos.: 61/278,240, filed Oct. 5, 2009; 61/336,911, filed Jan. 28,2010; 61/343,737 filed May 3, 2010; 61/395,564 filed May 14, 2010;61/395,752 filed May 17, 2010; 61/396,390 filed May 26, 2010; 61/398,807filed Jul. 1, 2010; 61/400,504 filed Jul. 29, 2010; 61/402,959 filedSep. 8, 2010; 61/403,696 filed Sep. 20, 2010; and 61/403,915 filed Sep.23, 2010, all of which are incorporated by reference herein. Thisapplication is also a continuation-in-part of U.S. patent applicationSer. No. 12/802,849 filed Jun. 15, 2010 that claims the benefit of thefollowing U.S. Provisional Patent Application Ser. Nos.: 61/268,708filed Jun. 15, 2009; 61/270,754, filed Jul. 13, 2009; 61/336,911 filedJan. 28, 2010; 61/395,564 filed May 14, 2010; 61/395,752 filed May 17,2010; and 61/396,390 filed May 26, 2010, all of which are incorporatedby reference herein.

BACKGROUND OF THE INVENTION

The present invention is directed to polyaxial bone screws for use inbone surgery, particularly spinal surgery and particularly to suchscrews with compression or pressure inserts and expansion lock splitretainers to snap over, capture and retain the bone screw shank head inthe receiver member assembly and later fix the bone screw shank withrespect to the receiver assembly.

Bone screws are utilized in many types of spinal surgery in order tosecure various implants to vertebrae along the spinal column for thepurpose of stabilizing and/or adjusting spinal alignment. Although bothclosed-ended and open-ended bone screws are known, open-ended screws areparticularly well suited for connections to rods and connector arms,because such rods or arms do not need to be passed through a closedbore, but rather can be laid or urged into an open channel within areceiver or head of such a screw. Generally, the screws must be insertedinto the bone as an integral unit along with the head, or as apreassembled unit in the form of a shank and pivotal receiver, such as apolyaxial bone screw assembly.

Typical open-ended bone screws include a threaded shank with a pair ofparallel projecting branches or arms which form a yoke with a U-shapedslot or channel to receive a rod. Hooks and other types of connectors,as are used in spinal fixation techniques, may also include similar openends for receiving rods or portions of other fixation and stabilizationstructure.

A common approach for providing vertebral column support is to implantbone screws into certain bones which then in turn support a longitudinalstructure such as a rod, or are supported by such a rod. Bone screws ofthis type may have a fixed head or receiver relative to a shank thereof,or may be of a polyaxial screw nature. In the fixed bone screws, the rodreceiver head cannot be moved relative to the shank and the rod must befavorably positioned in order for it to be placed within the receiverhead. This is sometimes very difficult or impossible to do. Therefore,polyaxial bone screws are commonly preferred. Open-ended polyaxial bonescrews typically allow for a loose or floppy rotation of the head orreceiver about the shank until a desired rotational position of thereceiver is achieved by fixing such position relative to the shankduring a final stage of a medical procedure when a rod or otherlongitudinal connecting member is inserted into the receiver, followedby a locking screw or other closure. This floppy feature can be, in somecases, undesirable and make the procedure more difficult. Also, it isoften desirable to insert the bone screw shank separate from thereceiver or head due to its bulk which can get in the way of what thesurgeon needs to do. Such screws that allow for this capability aresometimes referred to as modular polyaxial screws.

With specific reference to modular snap-on or pop-on polyaxial pediclescrew systems having shank receiver assemblies, the prior art has shownand taught the concept of the receiver and certain retainer partsforming an assembly wherein a contractile locking engagement between theparts is created to fix the shank head with respect to the receiver andretainer. The receiver and shank head retainer assemblies in the priorart have included a slotted contractile retainer ring and/or a lowerpressure slotted insert with an expansion and contraction collet-type ofstructure having contractile locking engagement for the shank head dueto direct contact between the retainer and/or the collet structure withthe receiver resulting in contraction of the slotted retainer ringand/or the collet-type structure of the insert against the shank head.The receiver and slotted insert have generally included tapered lockingengagement surfaces.

The prior art for modular polyaxial screw assemblies has also shown andtaught that the contact surfaces on the outside of the slotted colletand/or retainer and the inside of the receiver, in addition to beingtapered, can be conical, radiused, spherical, curvate, multi-curvate,rounded, as well as other configurations to create a contractile type oflocking engagement for the shank head with respect to the receiver.

In addition, the prior art for modular polyaxial screw assemblies hasshown and taught that the shank head can both enter and escape from acollet-like structure on the insert or from the retainer when the insertor retainer is in the up position and within an expansion recess orchamber of the receiver. This is the case unless the slotted insertand/or the slotted retainer are blocked or constrained from being ableto be pushed or manipulated back up into the receiver bore or cavity, orunless the screw assemblies are otherwise uniquely configured to preventthis from happening.

SUMMARY OF THE INVENTION

The present invention differentiates from the prior art by not allowingthe receiver to be removed from the shank head once the parts aresnapped-on and connected. This is true even if the retainer can go backup into the expansion chamber. This approach or design has been found tobe more secure and to provide more resistance to pull-out forcescompared to the prior art for modular polyaxial screw designs.Collect-like structures extending downwardly from lower pressureinserts, when used in modular polyaxial screw designs, as shown in theprior art, have been found to be somewhat weak with respect to pull-outforces encountered during some spinal reduction procedures. The presentinvention is designed to solve these problems.

The present invention also differentiates from the prior art byproviding a split retainer ring with inner friction fit surfaces thatmay be partially radiused that do not participate in the final lockingengagement for the shank head with respect to the receiver. In addition,the retainer ring itself for the present invention is uniquelycharacterized by a base portion providing expansion to receive andcapture the shank head and then having expansion (not contraction)locking engagement between the shank head and the retainer ring base andbetween the retainer ring base and horizontal and vertical loadingsurfaces near a bottom opening of the receiver.

The expansion-only retainer ring base portion in the present inventionis positioned entirely below the shank head hemisphere in the receiverand can be a stronger, more substantial structure to resist larger pullout forces on the assembly. The retainer ring base can also be bettersupported on a generally horizontal loading surface near the loweropening in the bottom of the receiver. This design has been found to bestronger and more secure when compared to that of the prior art whichuses some type of contractile locking engagement between the parts, asdescribed above; and, again, once assembled it cannot be disassembled.

Thus, a polyaxial bone screw assembly according to the inventionincludes a shank having an integral upper portion or integral radiusedor spherical head and a body for fixation to a bone; a separate receiverdefining an upper open channel, a central bore, a lower cavity and alower opening; a top drop and turn in place lower compression insert;and a friction fit resilient expansion locking split retainer forcapturing the shank head in the receiver lower cavity, the shank headbeing frictionally engaged with, but still movable in a non-floppymanner with respect to the friction fit retainer and the receiver priorto locking of the shank into a desired configuration. The shank isfinally locked into a fixed position relative to the receiver byfrictional engagement between the insert and a lower split ring-likeportion of the retainer, as described previously, due to a downwardforce placed on the compression insert by a closure top pressing on arod, or other longitudinal connecting member, captured within thereceiver bore and channel. In the illustrated embodiments, retainers andcompression inserts are downloaded into the receiver, but uploadedembodiments are also foreseen. The shank head can be positioned into thereceiver lower cavity at the lower opening thereof prior to or afterinsertion of the shank into bone. In some embodiments, the compressioninsert may include a lock and release feature for independent locking ofthe polyaxial mechanism so the screw can be used like a fixed monoaxialscrew. Also, in some embodiments the shank can be cannulated forminimally invasive surgery applications. The retainer includes upwardlyextending tangs that are deployed in the receiver cavity so that theretainer and captured shank head are stabilized and retained in theregion of the receiver locking chamber once, but are free to rotatewithin the cavity. In this way, the shank head and retainer arepartially constrained and cannot go back up into the receiver cavity,but can be manipulated there-within.

Again, a pre-assembled receiver, compression insert and friction fitsplit retainer may be “pushed-on”, “snapped-on” or “popped-on” to theshank head prior to or after implantation of the shank into a vertebra.Such a “snapping on” procedure includes the steps of uploading the shankhead into the receiver lower opening, the shank head pressing againstthe base portion of the split retainer ring and expanding the resilientlower open retainer portion out into an expansion portion or chamber ofthe receiver cavity followed by an elastic return of the retainer backto a nominal or near nominal shape thereof after the hemisphere of theshank head or upper portion passes through the lower ring-like portionof the retainer. The shank head enters into friction fit engagement withportions of the retainer, defined at least in part, by inner tangs ofthe retainer. The retainer snapping onto the shank head as the retainerreturns to a neutral or close to neutral orientation, providing anon-floppy connection between the retainer and the shank head. In theillustrated embodiments, when the shank is ultimately locked between thecompression insert and the lower portion of the retainer, a lowerretainer edge surface locks against the shank head. The final fixationoccurs as a result of a locking expansion-type of contact between theshank head and the lower edge portion of the split retainer and anexpansion-type of non-tapered locking engagement between the lowerportion of the retainer ring and the locking chamber in the lowerportion of the receiver cavity. The retainer can expand more in theupper portion or expansion chamber of the receiver cavity to allow theshank head to pass through, but has restricted expansion to retain theshank head when the retainer lower ring portion is against the lockingchamber surfaces in the lower portion of the receiver cavity and theshank head is forced down against the retainer ring during finallocking. In some embodiments, when the polyaxial mechanism is locked,the pressure or compression insert is forced or wedged against a surfaceof the receiver resulting in an interference locking engagement,allowing for adjustment or removal of the rod or other connecting memberwithout loss of a desired angular relationship between the shank and thereceiver. This independent locking feature allows the polyaxial screw tofunction like a fixed monoaxial screw.

The lower pressure insert may also be configured to be independentlylocked by a tool or instrument, thereby allowing the pop-on polyaxialscrew to be distracted, compressed and/or rotated along and around therod to provide for improved spinal correction techniques. Such a toolengages the receiver from the sides and then engages outwardly extendingwinged arms of the insert to force or wedge the insert down into alocked position within the receiver. With the tool still in place andthe correction maintained, the rod is then locked within the receiverchannel by a closure top followed by removal of the tool. This processmay involve multiple screws all being manipulated simultaneously withmultiple tools to achieve the desired correction.

Objects of the invention further include providing apparatus and methodsthat are easy to use and especially adapted for the intended use thereofand wherein the tools are comparatively inexpensive to produce. Otherobjects and advantages of this invention will become apparent from thefollowing description taken in conjunction with the accompanyingdrawings wherein are set forth, by way of illustration and example,certain embodiments of this invention.

The drawings constitute a part of this specification and includeexemplary embodiments of the present invention and illustrate variousobjects and features thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a polyaxial bone screwassembly according to the present invention including a shank, areceiver, an open friction fit retainer and a top drop and turn in placelower compression insert, further shown with a portion of a longitudinalconnecting member in the form of a rod and a closure top.

FIG. 2 is an enlarged top plan view of the shank of FIG. 1.

FIG. 3 is a reduced cross-sectional view taken along the line 3-3 ofFIG. 2.

FIG. 4 is an enlarged side elevational view of the receiver of FIG. 1.

FIG. 5 is a perspective view of the receiver of FIG. 4.

FIG. 6 is a front elevational view of the receiver of FIG. 4.

FIG. 7 is a bottom plan view of the receiver of FIG. 4.

FIG. 8 is a top plan view of the receiver of FIG. 4.

FIG. 9 is a cross-sectional view taken along the line 9-9 of FIG. 8.

FIG. 10 is a cross-sectional view taken along the line 10-10 of FIG. 8.

FIG. 11 is an enlarged perspective view of the retainer of FIG. 1.

FIG. 12 is a front elevational view of the retainer of FIG. 11.

FIG. 13 is a top plan view of the retainer of FIG. 11.

FIG. 14 is a bottom plan view of the retainer of FIG. 11.

FIG. 15 is an enlarged cross-sectional view taken along the line 15-15of FIG. 13.

FIG. 16 is another perspective view of the retainer of FIG. 11.

FIG. 17 is an enlarged perspective view of the insert of FIG. 1.

FIG. 18 is a side elevational view of the insert of FIG. 17.

FIG. 19 is another perspective view of the insert of FIG. 17.

FIG. 20 is a top plan view of the insert of FIG. 17.

FIG. 21 is a bottom plan view of the insert of FIG. 17.

FIG. 22 is an enlarged cross-sectional view taken along the line 22-22of FIG. 20.

FIG. 23 is an enlarged cross-sectional view taken along the line 23-23of FIG. 20.

FIG. 24 is an enlarged front elevational view of the retainer andreceiver of FIG. 1 with portions of the receiver broken away to show thedetail thereof, the retainer being shown downloaded into the receiver(in phantom) to a partially inserted stage of assembly.

FIG. 25 is a front elevational view of the retainer and receiver withportions broken away, similar to what is shown in FIG. 24, showing theretainer in a subsequent stage of assembly and in a maximum state ofcompression.

FIG. 26 is a bottom plan view of the receiver and retainer of FIG. 25.

FIG. 27 is an enlarged front elevational view of the retainer andreceiver with portions broken away, similar to what is shown in FIG. 25,showing the retainer positioned below the receiver spring tabs and alsorotated about a central axis thereof, such rotation not necessary forassembly but provided herein to aid in viewing the drawings.

FIG. 28 is a cross-sectional view taken along the line 28-28 of FIG. 27.

FIG. 29 is an enlarged front elevational view of the retainer andreceiver with portions broken away, similar to what is shown in FIG. 27,showing the retainer in a slightly lower position within the receiverand further including the insert in side elevation, in phantom, beingdownloaded into the receiver and the insert shown in solid lines withportions broken away when at a location suitable for rotation within thereceiver.

FIG. 30 is a front elevational view of the retainer and receiver withportions broken away, similar to what is shown in FIG. 29, furthershowing the insert being partially rotated within the receiver withreceiver spring tabs being pushed outwardly during such rotation.

FIG. 31 is a reduced front elevational view with portions broken away,similar to FIG. 30, showing the insert fully rotated within the receiverwith the receiver spring tabs pressing into apertures of the insert andwith retainer spring tabs located to push resiliently outwardly againstthe receiver, holding the retainer against the receiver and keeping theretainer in an upward position during shipping and assembly with theshank of FIG. 1, the figure further showing the shank of FIG. 1 in anenlarged and partial front elevational view and implanted into a portionof a vertebra, a hemisphere of the shank head and the vertebra portionare both shown in phantom.

FIG. 32 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 31, and further showing the shank in afirst stage of assembly with the receiver and retainer.

FIG. 33 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 32, showing the retainer lower portion inan expanded state about a mid-portion of the shank head.

FIG. 34 is a reduced and partial front elevational view with portionsbroken away, similar to FIG. 33, the spherical shank upper portion orhead shown fully captured by the retainer.

FIG. 35 is a reduced and partial front elevational view with portionsbroken away, similar to FIG. 34, the shank upper portion with attachedretainer being shown pulled down into a seated position within the lowerreceiver cavity, the retainer spring tabs in a substantially neutralstate, extending outwardly and captured beneath a surface of thereceiver.

FIG. 36 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 35, the insert being shown pushed down intoa fully seated position within the lower receiver cavity by pressurebeing placed thereon from above by the rod and closure top of FIG. 1,also shown in partial front elevation, the insert being placed inlocking interference fit with the receiver.

FIG. 37 is a partial perspective view of the locked assembly of FIG. 36with portions broken away to show the detail thereof.

FIG. 38 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 36, but with the locking insert having beenpulled slightly upwardly by tooling (not shown) to result in an unlockedpolyaxial mechanism.

FIG. 39 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 36, but shown with the rod and closure topof FIG. 36 having been removed, the locking insert keeping the shanklocked in place, the figure further showing an alternative deformablerod and cooperating closure top being installed in the receiver.

FIG. 40 is a reduced and partial front elevational view with portionsbroken away, similar to FIG. 39, showing the alternative rod and closuretop fixed to the receiver.

FIG. 41 is a reduced side elevational view of the assembly of FIG. 1,shown fully assembled with the shank disposed at a twenty-two degree(cephalad) angle with respect to the receiver.

FIG. 42 is an enlarged and partial side elevational view of the assemblyof FIG. 41 with portions broken away to show the detail thereof.

FIG. 43 is a reduced side elevational view of the assembly of FIG. 1,shown fully assembled with the shank disposed at a thirty-three degree(caudad) angle with respect to the receiver.

FIG. 44 is a perspective view of the assembly of FIG. 43.

FIG. 45 is an enlarged and partial side elevational view of the assemblyof FIG. 43 with portions broken away to show the detail thereof.

FIG. 46 is an enlarged perspective view of an alternative favored anglereceiver according to the invention having opposed lower concave steppedsurfaces for cooperating with the retainer of FIG. 1 to allow for up toa forty degree angle of the shank of FIG. 1 with respect to thealternative receiver.

FIG. 47 is an enlarged perspective view of an alternative non-lockinginsert according to the invention for use in lieu of the locking insertshown in FIG. 1.

FIG. 48 is another enlarged perspective view of the alternative insertof FIG. 47 with a portion broken away to show the detail thereof.

FIG. 49 is a side elevational view of the alternative insert of FIG. 47with a portion broken away to show the detail thereof.

FIG. 50 is an enlarged front elevational view of the receiver andretainer of FIG. 1 shown in a stage of assembly with the alternativeinsert of FIG. 47, also in front elevation, with portions broken away toshow the detail thereof.

FIG. 51 is an enlarged and partial front elevational view of thereceiver, retainer, rod and closure top of FIG. 1 shown fully assembledwith the alternative insert of FIG. 47, also in front elevation, withportions broken away to show the detail thereof.

FIG. 52 is a perspective view of a sleeve according to the invention foruse with bone screw assemblies of the invention.

FIG. 53 is a front elevational view of the sleeve of FIG. 52.

FIG. 54 is a top plan view of the sleeve of FIG. 52.

FIG. 55 is a bottom plan view of the sleeve of FIG. 52.

FIG. 56 is a side elevational view of the sleeve of FIG. 52 withportions broken away to show the detail thereof.

FIG. 57 is a reduced perspective view of the sleeve of FIG. 52 shownassembled with a bone screw assembly of FIG. 1 (shown partiallyexploded), with the rod of FIG. 1 being replaced by a cord, and furthershowing a pair of transparent compressible cylindrical spacers locatedabout the cord and at either side of the sleeve.

FIG. 58 is an enlarged cross-sectional view taken along the line 58-58of FIG. 57 with the closure top shown mated with the receiver.

FIG. 59 is a reduced cross-sectional view taken along the line 59-59 ofFIG. 58.

FIG. 60 is a partially exploded, front elevational view of the sleeve ofFIG. 52 and bone screw assembly of FIG. 1, but with the rod and closuretop of FIG. 1 being replaced by a cord and an alternative cord-lockingclosure top.

FIG. 61 is a front elevational view, similar to FIG. 60, with portionsbroken away to show the detail thereof, showing the alternativecord-locking closure top engaging the sleeve and the receiver.

FIG. 62 is an enlarged and partial, perspective view of the assemblyshown in FIG. 57, but with one of the spacers being replaced with abumper (shown transparent) and blocker/set screw combination, shownpartially exploded.

FIG. 63 is an enlarged and partial side elevational view of the assemblyof FIG. 62 with portions broken away to show the detail thereof, showingthe set screw fixing the cord with respect to the blocker and the cordin slidable relationship with the bone screw.

FIG. 64 is an enlarged perspective view of the assembly of FIG. 1, butwith the rod and closure top of FIG. 1 being replaced by a secondalternative sleeve with rectangular faces, a cord and alternativecord-locking closure top of the invention.

FIG. 65 is a partial and partially exploded front elevational view ofthe assembly of FIG. 64.

FIG. 66 is an enlarged and partial front elevational view of theassembly of FIG. 64 with portions broken away to show the detailthereof.

FIG. 67 is an enlarged perspective view of the alternative sleeve ofFIG. 64.

FIG. 68 is a top plan view of the alternative sleeve of FIG. 67.

FIG. 69 is a bottom plan view of the alternative sleeve of FIG. 67.

FIG. 70 is a side elevational view of the alternative sleeve of FIG. 67with portions broken away to show the detail thereof.

FIG. 71 is a reduced perspective view of the assembly of FIG. 64 furthershown with an alternative compressible spacer having an oval profile(shown transparent).

FIG. 72 is a partial side elevational view of the assembly of FIG. 71further shown with a second alternative compressible spacer with an ovalprofile (also shown transparent).

FIG. 73 is an enlarged front elevational view of the compressible spacerwith oval profile shown in FIG. 71.

FIG. 74 is a top plan view of the spacer of FIG. 73.

FIG. 75 is an exploded perspective view of an alternative polyaxial bonescrew assembly according to the present invention including a shank, areceiver, an open friction fit retainer and a top drop and turn in placelower compression insert, further shown with a portion of a longitudinalconnecting member in the form of a rod and a closure top.

FIG. 76 is an enlarged side elevational view of the receiver of FIG. 75.

FIG. 77 is a reduced front elevational view of the receiver of FIG. 76.

FIG. 78 is a cross-sectional view taken along the line 78-78 of FIG. 76.

FIG. 79 is an enlarged cross-sectional view taken along the line 79-79of FIG. 77.

FIG. 80 is an enlarged front elevational view of the retainer of FIG.75.

FIG. 81 is an enlarged and partial front elevational view of theretainer of FIG. 80.

FIG. 82 is a perspective view of the retainer of FIG. 80.

FIG. 83 is another perspective view of the retainer of FIG. 80.

FIG. 84 is a top plan view of the retainer of FIG. 80.

FIG. 85 is a bottom plan view of the retainer of FIG. 80.

FIG. 86 is an enlarged cross-sectional view taken along the line 86-86of FIG. 84.

FIG. 87 is an enlarged perspective view of the insert of FIG. 75.

FIG. 88 is a side elevational view of the insert of FIG. 87 withportions broken away to show the detail thereof.

FIG. 89 is a front elevational view of the insert of FIG. 87 withportions broken away to show the detail thereof.

FIG. 90 is an enlarged front elevational view of the retainer andreceiver of FIG. 75 with portions of the receiver broken away to showthe detail thereof, the retainer being shown downloaded into thereceiver to a partially inserted stage of assembly.

FIG. 91 is a perspective view of the retainer and receiver with portionsbroken away, similar to what is shown in FIG. 90, showing the retainerin a subsequent stage of assembly and in a maximum state of compression.

FIG. 92 is a front elevational view of the retainer and receiver withportions broken away, similar to what is shown in FIG. 91, showing theretainer positioned below the receiver spring tabs and also rotatedabout a central axis thereof, such rotation not necessary for assemblybut provided herein to aid in viewing the drawings.

FIG. 93 is an enlarged front elevational view of the retainer andreceiver with portions broken away, similar to what is shown in FIG. 27,showing the retainer fully deployed within the receiver cavity andfurther including the insert in side elevation, being downloaded intothe receiver and at a location suitable for rotation within thereceiver.

FIG. 94 is a front elevational view of the retainer and receiver withportions broken away, similar to what is shown in FIG. 93, furthershowing the insert being rotated to a desired position in the receiverwith the receiver spring tabs pressing into apertures of the insert andfurther showing the retainer tangs being squeezed (tool not shown) inpreparation for moving the retainer upwardly toward the insert.

FIG. 95 is a front elevational view of the retainer and receiver withportions broken away, similar to what is shown in FIG. 94, the retainershown in a position wherein the tangs push resiliently outwardly againstthe receiver, holding the retainer against the receiver and keeping theretainer in an upward position during shipping and assembly with theshank of FIG. 75, the figure further showing the shank of FIG. 75 in anenlarged and partial front elevational view at an early stage ofassembly with the retainer, a hemisphere of the shank head is shown inphantom.

FIG. 96 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 95, showing the retainer lower portion inan expanded state about a mid-portion of the shank head.

FIG. 97 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 96, the spherical shank upper portion orhead shown fully captured by the retainer.

FIG. 98 is a reduced and partial front elevational view with portionsbroken away, similar to FIG. 97, the shank upper portion with attachedretainer being shown pulled down into a seated position within the lowerreceiver cavity, the retainer tangs in a substantially neutral state,extending outwardly and captured beneath a surface of the receiver.

FIG. 99 is a reduced and partial front elevational view with portionsbroken away, similar to FIG. 98, the insert being shown pushed down intoa fully seated position within the lower receiver cavity by pressurebeing placed thereon from above by the rod and closure top of FIG. 75,also shown in partial front elevation, the insert being placed inlocking interference fit with the receiver.

FIG. 100 is an enlarged and partial front elevational view with portionsbroken away of the assembly as shown in FIG. 99.

FIG. 101 is an enlarged and partial perspective view of the assembly ofFIG. 75, shown fully assembled with the shank disposed at a twentydegree (cephalad) angle with respect to the receiver.

FIG. 102 is an enlarged and partial perspective view of the assembly ofFIG. 75, shown fully assembled with the shank disposed at a thirtydegree (caudad) angle with respect to the receiver.

FIG. 103 is an enlarged perspective view of an alternative favored anglereceiver according to the invention having opposed lower concave steppedsurfaces, shown cooperating with the retainer of FIG. 75.

FIG. 104 is an enlarged perspective view of an alternative non-lockinginsert according to the invention for use in lieu of the locking insertshown in FIG. 75.

FIG. 105 is an enlarged front elevational view of the alternative insertof FIG. 104 shown in a stage of assembly with the receiver and retainerof FIG. 75, with portions broken away to show the detail thereof.

FIG. 106 is an enlarged and partial front elevational view of thereceiver, retainer, rod and closure top of FIG. 75 shown fully assembledwith the alternative insert of FIG. 104, also in front elevation, withportions broken away to show the detail thereof.

FIG. 107 is an exploded perspective view of another alternativepolyaxial bone screw assembly according to the present inventionincluding a shank, a receiver, an open friction fit retainer and a topdrop and turn in place lower compression insert, further shown with aportion of a longitudinal connecting member in the form of a rod and aclosure top.

FIG. 108 is an enlarged and partial front elevational view of the shankof FIG. 107.

FIG. 109 is an enlarged front elevational view of the receiver of FIG.107 with portions broken away to show the detail thereof.

FIG. 110 is side elevational view of the receiver of FIG. 109 withportions broken away to show the detail thereof.

FIG. 111 is an enlarged an partial front elevational view of thereceiver of FIG. 109.

FIG. 112 is an enlarged perspective view of the retainer of FIG. 107.

FIG. 113 is a top plan view of the retainer of FIG. 112.

FIG. 114 is a reduced bottom plan view of the retainer of FIG. 112.

FIG. 115 is a reduced cross-sectional view taken along the line 115-115of FIG. 113.

FIG. 116 is a reduced cross-sectional view taken along the line 116-116of FIG. 113.

FIG. 117 is an enlarged front elevational view of the insert of FIG. 107with portions broken away to show the detail thereof.

FIG. 118 is a side elevational view of the insert of FIG. 117 withportions broken away to show the detail thereof.

FIG. 119 is an enlarged front elevational view of the retainer andreceiver of FIG. 107 with portions of the receiver broken away to showthe detail thereof, the retainer being shown downloaded into thereceiver to a partially inserted stage of assembly.

FIG. 120 is a perspective view of the retainer and receiver withportions broken away, similar to what is shown in FIG. 119, showing theretainer in a subsequent stage of assembly and in a maximum state ofcompression.

FIG. 121 is a front elevational view of the retainer and receiver withportions broken away, similar to what is shown in FIG. 119, showing theretainer tangs fully deployed within the receiver cavity, but theretainer not fully seated within the receiver cavity.

FIG. 122 is an enlarged and partial front elevational view of theassembly as shown in FIG. 121.

FIG. 123 is a front elevational view of the retainer and receiver withportions broken away, similar to FIG. 121 and further including theinsert in side elevation, being downloaded into the receiver and at alocation suitable for rotation within the receiver.

FIG. 124 is a reduced front elevational view of the retainer andreceiver with portions broken away, similar to what is shown in FIG.123, further showing the insert being rotated to a desired position inthe receiver with the receiver spring tabs pressing into apertures ofthe insert and further showing the shank of FIG. 107 in an enlarged andpartial front elevational view at an early stage of assembly with theretainer.

FIG. 125 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 124, showing the retainer lower portion inan expanded state about a mid-portion of the shank head.

FIG. 126 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 125, the spherical shank upper portion orhead shown fully captured by the retainer and the shank head being shownpressing up against the insert.

FIG. 127 is a reduced and partial front elevational view with portionsbroken away, similar to FIG. 126, the shank upper portion being shownpartially pulled down into the receiver cavity, the retainer outer tangsin a substantially neutral state and the inner tangs contacting ridgeson the shank head.

FIG. 128 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 127, showing a further pull-down of theshank head with respect to inner retainer tangs.

FIG. 129 is an enlarged and partial front elevational view with portionsbroken away, similar to FIG. 128, showing a further pull-down of theshank head and attached retainer, the retainer being pulled down to aseated position within the receiver cavity.

FIG. 130 is a reduced and partial front elevational view with portionsbroken away, similar to FIG. 129, the insert being pushed down into afully seated position within the lower receiver cavity by pressure beingplaced thereon from above by the rod and closure top of FIG. 107, alsoshown in partial front elevation, the insert being placed in lockinginterference fit with the receiver.

FIG. 131 is an enlarged and partial front elevational view with portionsbroken away of the assembly of FIG. 130, but with the closure toploosened and the rod lifted up, the insert however remaining locked intoplace against the receiver, maintaining the retainer and shank in alocked position.

FIG. 132 is a reduced and partial front elevational view with portionsbroken away of the assembly of FIG. 131 with the exception that the rodand closure top have been removed and replaced with an alternativedeformable rod and cooperating alternative closure top.

FIG. 133 is an enlarged and partial perspective view of the assembly ofFIG. 107, shown fully assembled with the shank disposed at a twentydegree (cephalad) angle with respect to the receiver.

FIG. 134 is an enlarged and partial perspective view of the assembly ofFIG. 107, shown fully assembled with the shank disposed at a thirtydegree (caudad) angle with respect to the receiver.

FIG. 135 is an enlarged perspective view of an alternative non-lockinginsert according to the invention for use in lieu of the locking insertshown in FIG. 107.

FIG. 136 is an enlarged front elevational view of the alternative insertof FIG. 135 shown in a stage of assembly with the receiver and retainerof FIG. 107, with portions broken away to show the detail thereof.

FIG. 137 is an enlarged and partial front elevational view of thereceiver, retainer, rod and closure top of FIG. 107 shown fullyassembled with the alternative insert of FIG. 135, also in frontelevation, with portions broken away to show the detail thereof.

DETAILED DESCRIPTION OF THE INVENTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention, which may be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present invention in virtually anyappropriately detailed structure. It is also noted that any reference tothe words top, bottom, up and down, and the like, in this applicationrefers to the alignment shown in the various drawings, as well as thenormal connotations applied to such devices, and is not intended torestrict positioning of the bone attachment structures in actual use.

With reference to FIGS. 1-38 and 41-46, the reference number 1 generallyrepresents a polyaxial bone screw apparatus or assembly according to thepresent invention. The assembly 1 includes a shank 4, that furtherincludes a body 6 integral with an upwardly extending upper portion orhead 8; a receiver 10; a friction fit retainer 12, and a crown-likecompression or pressure insert 14. The receiver 10, retainer 12 andcompression insert 14 are initially assembled and may be furtherassembled with the shank 4 either prior or subsequent to implantation ofthe shank body 6 into a vertebra 17, as will be described in greaterdetail below. FIGS. 1 and 36-37 further show a closure structure 18 forcapturing a longitudinal connecting member, for example, a rod 21 whichin turn engages the compression insert 14 that presses against the shankhead 8 into fixed frictional contact with the retainer 12, so as tocapture, and fix the longitudinal connecting member 21 within thereceiver 10 and thus fix the member 21 relative to the vertebra 17. Thereceiver 10 and the shank 4 cooperate in such a manner that the receiver10 and the shank 4 can be secured at any of a plurality of angles,articulations or rotational alignments relative to one another andwithin a selected range of angles both from side to side and from frontto rear, to enable flexible or articulated engagement of the receiver 10with the shank 4 until both are locked or fixed relative to each othernear the end of an implantation procedure. The illustrated rod 21 ishard, stiff, non-elastic and cylindrical, having an outer cylindricalsurface 22. In some embodiments, the rod 21 may be elastic, deformableand/or of different materials and cross-sectional geometries (see, e.g.,FIGS. 39 and 40). It is foreseen that in other embodiments (not shown)the closure top could deform the rod and press directly on the insert14.

The shank 4, best illustrated in FIGS. 1-3, is elongate, with the shankbody 6 having a helically wound bone implantable thread 24 (single ordual lead thread form and different thread types) extending from near aneck 26 located adjacent to the upper portion or head 8, to a tip 28 ofthe body 6 and extending radially outwardly therefrom. During use, thebody 6 utilizing the thread 24 for gripping and advancement is implantedinto the vertebra 17 leading with the tip 28 and driven down into thevertebra with an installation or driving tool (not shown), so as to beimplanted in the vertebra to a location at or near the neck 26, as shownin FIG. 31, for example, and more fully described in the paragraphsbelow. The shank 4 has an elongate axis of rotation generally identifiedby the reference letter A.

The neck 26 extends axially upward from the shank body 6. The neck 26may be of the same or is typically of a slightly reduced radius ascompared to an adjacent upper end or top 32 of the body 6 where thethread 24 terminates. Further extending axially and outwardly from theneck 26 is the shank upper portion or head 8 that provides a connectiveor capture apparatus disposed at a distance from the upper end 32 andthus at a distance from the vertebra 17 when the body 6 is implanted insuch vertebra.

The shank upper portion 8 is configured for a pivotable connectionbetween the shank 4 and the retainer 12 and receiver 10 prior to fixingof the shank 4 in a desired position with respect to the receiver 10.The shank upper portion 8 has an outer, convex and substantiallyspherical surface 34 that extends outwardly and upwardly from the neck26 that in some embodiments terminates at a substantially a circular orpolygonal edge or rim 38. In the illustrated embodiment, afrusto-conical surface 39 extends from the spherical surface 34 inwardlyto the top edge 38, providing additional clearance during pivoting ofthe shank with respect to the receiver 10 and the insert 14. Thespherical surface 34 has an outer radius configured for temporaryfrictional, non-floppy, sliding cooperation with one or more edgesand/or surfaces of the retainer 12, as well as ultimate frictionalengagement with the retainer 12 at a lower inner edge thereof andultimate frictional engagement with the insert 14 at an inner partiallyspherical surface thereof and/or stepped or ridged surfaces thereof, aswill be discussed more fully in the paragraphs below. In FIG. 1 and someof the other figures, a dotted line 40 designates a hemisphere of thespherical surface 34. The spherical surface 34 shown in the presentembodiment is substantially smooth, but in some embodiments may includea roughening or other surface treatment and is sized and shaped forcooperation and ultimate frictional engagement with the compressioninsert 14 as well as ultimate frictional engagement with a lowerring-like edge of the retainer 12. The shank spherical surface 34 islocked into place exclusively by the insert 14 and the retainer 12 loweredged portion and not by inner surfaces defining the receiver cavity.

A counter sunk and stepped or graduated annular seating surface or base45 partially defines a portion of an internal drive feature or imprint46. In some embodiments of the invention, the surface 45 issubstantially planar. The illustrated internal drive feature 46 is anaperture formed in the top 38 and has a hex shape designed to receive atool (not shown) of an Allen wrench type, into the aperture for rotatingand driving the bone screw shank 4 into the vertebra 17. It is foreseenthat such an internal tool engagement structure may take a variety oftool-engaging forms and may include one or more apertures of variousshapes, such as a pair of spaced apart apertures or a multi-lobular orstar-shaped aperture. The graduated seat or base surfaces 45 of thedrive feature 46 are disposed substantially perpendicular to the axis Awith the drive feature 46 otherwise being coaxial with the axis A. Asillustrated in FIGS. 2 and 3, the drive seat 45 having beveled orstepped surfaces advantageously further enhances gripping with thedriving tool. In operation, the driving tool (not shown) is received inthe internal drive feature 46, being seated at the base 45 and engagingthe faces of the drive feature 46 for both driving and rotating theshank body 6 into the vertebra 17, either before or after the shank 4 isconnected to the receiver 10 via the retainer 12, the driving toolextending into the receiver 10 when the shank 4, retainer 12 andreceiver 10 combination is driven into the vertebra 17.

The shank 4 shown in the drawings is cannulated, having a small centralbore 50 extending an entire length of the shank 4 along the axis A. Thebore 50 is defined by an inner cylindrical wall of the shank 4 and has acircular opening at the shank tip 28 and an upper circular openingcommunicating with the external drive 46 at the driving seat 45. Thebore 50 is coaxial with the threaded body 6 and the upper portion orhead 8. The bore 50 provides a passage through the shank 4 interior fora length of wire (not shown) inserted into the vertebra 17 prior to theinsertion of the shank body 6, the wire providing a guide for insertionof the shank body 6 into the vertebra 17. It is foreseen that the shankcould be solid and made of different materials, including metal andnon-metals.

To provide a biologically active interface with the bone, the threadedshank body 6 may be coated, perforated, made porous or otherwisetreated. The treatment may include, but is not limited to a plasma spraycoating or other type of coating of a metal or, for example, a calciumphosphate; or a roughening, perforation or indentation in the shanksurface, such as by sputtering, sand blasting or acid etching, thatallows for bony ingrowth or ongrowth. Certain metal coatings act as ascaffold for bone ingrowth. Bio-ceramic calcium phosphate coatingsinclude, but are not limited to: alpha-tri-calcium phosphate andbeta-tri-calcium phosphate (Ca₃(PO₄)₂, tetra-calcium phosphate(Ca₄P₂O₉), amorphous calcium phosphate and hydroxyapatite(Ca₁₀(PO₄)₆(OH)₂). Coating with hydroxyapatite, for example, isdesirable as hydroxyapatite is chemically similar to bone with respectto mineral content and has been identified as being bioactive and thusnot only supportive of bone ingrowth, but actively taking part in bonebonding.

With particular reference to FIGS. 1 and 4-10, the receiver 10 has agenerally U-shaped appearance with partially discontinuous cylindricalinner and outer profiles as well as planar and other curved surfaces.The receiver 10 has an axis of rotation B that is shown in FIG. 1 asbeing aligned with and the same as the axis of rotation A of the shank4, such orientation being desirable, but not required during assembly ofthe receiver 10 with the shank 4. After the receiver 10 is pivotallyattached to the shank 4, either before or after the shank 4 is implantedin a vertebra 17, the axis B is typically disposed at an angle withrespect to the axis A, as shown, for example, in FIGS. 41-46.

The receiver 10 includes a base 60 with various curved and mostlycylindrical surfaces 58 and opposed outer planar surfaces 59, the base60 defining a bore or inner cavity, generally 61, the base 60 beingintegral with a pair of opposed upstanding arms 62. At the base 60, theplanar surfaces 59 are located between the arms 62 and an inset surfaceportion 63 is located above and adjacent to each planar surface 59, eachinset surface portion 63 spanning between the pair of arms 62. The arms62 form a cradle and define a U-shaped channel 64 between the arms 62with an upper opening, generally 66, and a U-shaped lower channelportion or seat 68, the channel 64 having a width for operably snuglyreceiving the rod 21 or portion of another longitudinal connector orsleeve (such as those shown in FIGS. 52-74) between the arms 62, thechannel 64 communicating with the base cavity 61. Inner opposedsubstantially planar arm surfaces 69 partially define the channel 64above the curved seat 68 and partially define outer sides of each arminterior surface generally 70, that includes various inner cylindricalprofiles, an upper one of which is a partial helically wound guide andadvancement structure 72 located adjacent top surfaces 73 of each of thearms 62. In the illustrated embodiment, the guide and advancementstructure 72 is a partial helically wound interlocking flangeformconfigured to mate under rotation with a similar structure on theclosure structure 18, as described more fully below. However, it isforeseen that for certain embodiments of the invention, the guide andadvancement structure 72 could alternatively be a square-shaped thread,a buttress thread, a reverse angle thread or other thread-like ornon-thread-like helically wound discontinuous advancement structures,for operably guiding under rotation and advancing the closure structure18 downward between the arms 62, as well as eventual torquing when theclosure structure 18 abuts against the rod 21 or other longitudinalconnecting member. It is foreseen that the arms 62 could have break-offextensions.

An opposed pair of circular tool receiving and engaging apertures 74 areformed on outer substantially cylindrical surfaces 76 of the arms 62near the top surfaces 73. Furthermore, below each aperture 74 is athrough aperture or bore 77 also formed in and through each of the outersurfaces 76, each aperture 77 having a generally up-side down U-shape,the U-shape aperture defining a central inwardly and upwardly extendingholding tab 78 integral with the respective arm 62 at or near the base60, generally extending upwardly from the receiver base 60 and inwardlytoward the receiver axis B. Each aperture 77 extends through therespective arm surface 76 to the respective inner arm surface 70. Eachaperture 77 is located spaced from the adjacent aperture 74 and near oradjacent the receiver base 60. Some or all of the apertures 74 and 77may be used for holding the receiver 10 during assembly with the insert14, the retainer 12 and the shank 4, during the implantation of theshank body 6 into a vertebra when the shank is pre-assembled with thereceiver 10, and during assembly of the bone anchor assembly 1 with therod 21 or other longitudinal connecting member and the closure structure18. It is foreseen that tool receiving grooves or apertures may beconfigured in a variety of shapes and sizes and be disposed at otherlocations on the receiver arms 62.

The assembly 1 is typically provided to a user with the insert 14 beingheld within the receiver by the pair of inwardly extending holding tabs78, that are typically somewhat resilient, firmly holding the insert 14during assembly with the shank 4 and keeping the insert 14 relativelystationary with respect to the receiver 10 in an upward position betweenthe arms 62 until the insert 14 is pressed downwardly into lockingfriction fit with the shank upper portion or head 8. The holding tabs 78advantageously hold the insert 14 in a centered position (the insertarms being held in alignment with the receiver arms) during rotation andtorquing of the closure top 18 onto the rod 21 or other connectingmember. The opposed holding tabs 78 include outer surfaces and alsovarious inner surfaces for contacting the insert 14. The tab surfacesinclude a first outer surface 80 extending from the base 60 and slopingupwardly and slightly inwardly toward the receiver axis B. A secondinwardly sloping surface 81 is adjacent to the surface 80 and isdirected toward the axis B at an angle with respect thereto. The surface81 generally extends between the receiver outer periphery to the innerarm surface 70. Adjacent to the surface 81 is a tab top surface 82 thatruns toward the axis B and is substantially perpendicular thereto. Aninner insert engaging surface 84 is substantially perpendicular to thetop surface 82. The surface 84 is adjacent to a lower tab surface 85 andis perpendicular thereto. The insert engaging surface 84 is illustratedas having a slightly concave or cylindrical shape (may also be planar),sized and shaped for engagement with an outer substantially cylindricalsurface of the insert 14 as will be described in greater detail below.The lower surface 85 is parallel to the top surface 82. The holding tabs78 are stable, but exhibit some resilience, being pushed outwardly awayfrom the axis B during rotation of the insert 14 when the insert 14 isbeing assembled with the receiver 10 as shown, for example, in FIG. 30.Each holding tab 78 further includes opposed side surfaces 88 thatpartially define the U-shaped portion of the through aperture 77. Theaperture 77 is further defined by a top surface 89, opposed outersubstantially planar side surfaces 90 and a pair of spaced, curvedbottom surfaces 91.

Returning to the interior surface 70 of the receiver arms 62, locatedbelow the guide and advancement structure 72 is a discontinuouscylindrical surface 92 partially defining a run-out feature for theguide and advancement structure 72. The cylindrical surface 92 is sizedand shaped to receive the insert 14 as will be described in greaterdetail below. The surface 92 has a diameter slightly greater than agreater diameter of the guide and advancement structure 72. Theillustrated receiver 10 further includes sloped, stepped or chamferedsurface above and below the surface 92. The surface 92 is divided notonly by the U-shaped channel 64, but also by each of the throughapertures 77. A lower partially sloping or stepped ledge 94 at the baseof the cylindrical surface 92 slopes downwardly toward the receiver base60 and extends inwardly toward the axis B, the surface 94 terminating ata cylindrical surface 95 that extends completely around the receiverbase 60 and thus runs beneath each arm 62 and is adjacent to the lowerseat 68. The inner surface 95 thus defines an upper and inner portion ofthe receiver base 60. The cylindrical surface has a diameter slightlysmaller than the diameter of the surface 92. Lower legs of the throughaperture 77 partially defined by the surfaces 88 extend through thesurface 95. The surface 95 terminates at a ledge surface or chamberceiling 96 that extends outwardly away from the axis B, the surface 96being substantially perpendicular to the axis B, but could be oblique.The surface 96 is annular and defines an upper ceiling or stop of aretainer ring expansion portion or chamber of the inner cavity 61 thatis further defined by an adjacent outwardly sloping surface 97 and acylindrical surface 98 that is adjacent the surface 97. The surface 97acts as a stop for and slidingly cooperates with outwardly and upwardlyprojecting retainer tangs or panels as will be described in greaterdetail below. The cylindrical surface 98 has a diameter greater than thediameter of the cylindrical surface 95. The cylindrical surfaces 92, 95and 98 are all centrally aligned with and run parallel to the receiveraxis B. Lower surface portions 91 that define the through aperture 77extend into and through the sloping surface 97. The surface 98 defines acircumferential recess that is sized and shaped to receive the retainer12 as it expands around the shank upper portion 8 as the shank 8 movesupwardly toward the channel 64 during assembly. It is foreseen that therecess could be tapered or conical in configuration.

A pair of cylindrical surfaces 100 and 101 with an annular step surface102 therebetween as well as a lower annular step 103 located below andadjacent to the surface 101 provide a lower seat for the retainer 12 aswill be described in greater detail below. The surfaces 102 and 103 aresubstantially perpendicular to the surfaces 100 and 101 and the receiveraxis B. The surfaces 100, 101, 102 and 103 are located below thecylindrical surface 98 in the lower part of the base 60 and are sizedand shaped to closely receive and surround a lower base portion andlower skirt or sub-structure of the retainer 12 when the retainer is ina reduced deployment position as shown in FIGS. 35-38, for example.Thus, the cylindrical surface 101 has a diameter smaller than thediameter of the cylindrical surface 98 that defines the expansion areaor expansion chamber for the retainer 12. The surface 101 is joined orconnected to the surface 98 by one or more beveled, curved or conicaltransition step surfaces 104. The surfaces 104 allow for sliding andnominal or deployment positioning of the retainer 12 into the spacedefined by the surfaces 100 and 101 and ultimate seating of the retainer12 on the lower substantially horizontal annular surfaces 102 and 103.

Located below and adjacent to the annular seating surface 103 is a loweredge or rim surface 106 that communicates with a beveled or flaredbottom opening surface 107, the surface 107 communicating with anexterior base or bottom surface 108 of the base 60, defining a loweropening, generally 110, into the base cavity 61 of the receiver 10. Insome embodiments of the invention, it is foreseen that a curvate cut-outor cupped surface may be formed in a portion of the base surface 108, aswell as in portions of the surfaces 107, 106 and 100-104 locatedsubstantially centrally and directly below one of the arms 62. Such acupped surface may be sized and shaped for providing clearance for anincreased angle of articulation between the shank 4 and the receiver 10.

With particular reference to FIGS. 1 and 11-16, the lower open or splitfriction fit retainer 12, that operates to capture the shank upperportion 8 within the receiver 10 is shown. In certain stages of assemblyand operation, the retainer 12 is partially constrained within thereceiver, being captured within the receiver cavity 61 at a locationbelow the surface 97, the retainer 12 being rotatable with respect tothe receiver, but not pivotable thereto and not readily removable out ofthe receiver once deployed downward into the receiver cavity 61. Theretainer 12 has a central axis that is operationally the same as theaxis B associated with the receiver 10 when the shank upper portion 8and the retainer 12 are installed within the receiver 10. The retainer12 includes a substantially annular discontinuous body 115 having asubstantially cylindrical outer surface 116. Extending upwardly andoutwardly from the body 115, and integral thereto, is a superstructurethat includes two sets of flexible panels or tangs, in particular, innerpanels or tangs 117 and outer panels or tangs 118, the panels 117 and118 extending upwardly in aligned pairs, allowing for lateral spacesbetween the pairs panels or tangs to provide clearance during assemblyof the retainer 12 with the receiver 10 inner surfaces (see, e.g., FIGS.24 and 25). The illustrated embodiment includes six pairs of inner andouter panels or tangs 117, 118, but it is foreseen that more or fewerpanels or tangs may be used. The pairs of panels or tangs are generallyequally spaced about the body 115. Also integral to the body 115 are sixouter discontinuous cylindrical support surfaces 120, each surface 120located beneath one of the outer panels 118. Below the surfaces 120, thecylindrical surface 116 forms a lower outer cylindrical skirt 121 brokenonly by a gap that will be described in greater detail below. The outersurface 116 is adjacent a bottom surface 122 and also includes portions123 that are located between the outer panels 118. The surface portions123 are illustrated as substantially planar, but may be cylindrical,generally having a diameter that is the same as the surface 116. At eachof the panels 118, the surface 116 is adjacent to a ledge surface 124that in turn is adjacent to one of the outer support surfaces 120. Thelower skirt 121 and the ledge surfaces 124, as well as the surfaces 120are receiver seating surfaces as will be described in greater detailbelow. In the illustrated embodiment, transition areas where the surface116 meets the panels 117 and 118 or the retainer bottom 122 are curvedor chamfered. Each body portion 123 is adjacent to a body top surface126 that is substantially located between pairs of panels 117 and 118.Each top surface portion 126 is substantially planar and trapezoidal inouter profile.

The inner panels 117 each include a substantially planar outer surface128 and a concave inner surface 129, the surfaces 129 each beingpartially radiused and partially cylindrical, making up a discontinuouscurved surface sized and shaped for friction fit engagement with theshank head 8 as best shown in FIG. 13 and as will be described ingreater detail below. However, it is foreseen that the panel innersurfaces 129 may also be planar or include edges or other surfacesfeatures for gripping, but not locking the retainer 12 to the shank head8 during assembly and manipulation, but prior to locking of thepolyaxial mechanism of the bone screw assembly 1. The panels 117generally slant inwardly towards the central axis of the retainer 12 andthus ultimately inwardly toward the shank head 8. Each panel 117includes a top surface 130 that is substantially planar and runssubstantially parallel to the bottom surface 122 when the retainer is ina neutral position such as that shown in FIG. 15.

The outer panels 118 each have a planar outer surface 132, a planarinner surface 133 and a planar top surface 134 that slopes at an obliqueangle with respect to the retainer bottom surface 122. The surfaces 134are perpendicular to adjacent surfaces 132. The panels 118 generallyextend outwardly away from the panels 117 as well as outwardly andupwardly from the central axis of the retainer body 115. Each surface133 faces an outer surface 128 of one of the panels 117. The body topsurface 126 is reduced to a narrow strip between each pair of panels 117and 118. The panels 117 and 118 are resilient, the panels beingexpandable about the shank head 8 and the panels 118 being compressibleinwardly and resiliently holding against the receiver inner surfacesduring shipping and certain assembly steps. The panels 118 then returnto an original shape within the receiver cavity 61, capturing theretainer 12 within the receiver 10, but still allowing for rotation ofthe retainer 12 with respect to the receiver 10 about the receivercentral axis B.

The retainer ring 12 is made from a resilient material, such as astainless steel or titanium alloy, so that the retainer 12 body 115 maybe expanded and the tabs or panels 117 and 118 of the retainer may bemanipulated during various steps of assembly as will be described ingreater detail below. The retainer 12 has a central channel or hollowthrough bore, generally 141, that passes entirely through the retainer12 from the inner panel top surfaces 130 to the bottom surface 122 ofthe retainer body 115. Surfaces that define the channel or bore 141 atthe body 115 include a discontinuous inner lower frusto-conical surface143 adjacent to the retainer body bottom surface 122, a discontinuous,narrow substantially cylindrical surface 145 adjacent the frusto-conicalsurface 143 and a discontinuous annular step 146 located adjacent thecylindrical surface 145, the surface 146 being substantially parallel tothe bottom surface 122 and extending between the surface 145 and a lowercylindrical portion 129′ of the inner surface 129 that partially formsthe inner panels 117. The surfaces 145 and 146 terminate at an edge 147that is positioned and configured to engage the shank surface 34 as willbe described in greater detail below. The inner cylindrical surface 129′adjacent the step 146 forms a continuous inner cylindrical wall exceptat a slit, generally 148 that runs through the body 115. The slit 148creates a split or open ring retainer 12, the slit cutting entirelythrough the retainer body 115. In some embodiments, such a slit may runobtuse to the bottom surface 122. In the illustrated embodiment, theslit 148 runs substantially perpendicular to the surfaces 122. The slit148 is primarily for expansion of the retainer 12 during pop-on orsnap-on assembly with the shank head 8. However, the slit 148 alsocompresses during assembly with the receiver 10 as will be described ingreater detail below. The slit 148 extends between the body top surface126 and the bottom surface 122 and is located substantially centrallybetween two pairs of panels 117 and 118. Furthermore, at the location ofthe slit 148, a curved concave, cut-out surface 149 is formed in thebottom surface 122 and the frusto-conical surface 143. The cut-outsurface 149 also extends into the cylindrical surface 145 and removes aportion of the step 146 at either side of the slit 148. The surface 149is radiused or otherwise curved for engagement with the shank head 8 atthe surface 34 as will be described in greater detail below. In theillustrated embodiment, the cut-out surface 149 is located substantiallyequally on either side of the slit 148 to provide for a desirableincreased angle of orientation between the shank 8 and the retainer 12and thus a desirable increased angle of articulation between the shank 8and the receiver 10. The rotatability of the semi-constrained retainer12 with respect to the receiver 10 allows for manipulation and placementof such an increased angle of articulation to a location desired by asurgeon. The through slit 148 of the resilient retainer 12 is defined byfirst and second end surfaces, 152 and 153 disposed in substantiallyparallel spaced relation to one another when the retainer is in aneutral or nominal state. Both end surfaces 152 and 153 are disposedperpendicular to the bottom surface 122, but in some embodiments may bedisposed at an obtuse angle thereto. A width between the surfaces 152and 153 is narrow to provide stability to the retainer 12 duringoperation, but wide enough to allow for some compression of the retainerduring assembly as will be described in greater detail below. Becausethe retainer 12 is top loadable in a substantially neutral state andultimately expands during locking of the polyaxial mechanism, the widthof the slit 148 may be much smaller than might be required for a bottomloaded compressible retainer ring. It has been found that once theretainer 12 is expanded about the shank head 8, the retainer 12 mayreturn to a new nominal or neutral orientation in which a gap betweenthe surfaces 152 and 153 is slightly greater than the gap shown in thenominal state of FIG. 12, for example. As will be described in greaterdetail below, the assembly 1 advantageously provides for access to theinsert 14 and the retainer 12 to allow for pressing of the retainer 12down onto the receiver seat portions and reducing the retainer 12 intothe receiver 10 inner cylindrical surfaces as desired, prior to lockingof the assembly 1 with a rod and closure top.

With particular reference to FIGS. 1 and 17-23, the locking compressioninsert 14 is illustrated that is sized and shaped to be received by anddown-loaded into the receiver 10 at the upper opening 66. Thecompression insert 14 has an operational central axis that is the sameas the central axis B of the receiver 10. In operation, the insertadvantageously frictionally engages the bone screw shank upper portion 8as well as engaging the receiver 10 in an interference fit engagement,locking the shank 4 in a desired angular position with respect to thereceiver 10 that remains in such locked position even if, for example, arod and closure top are later removed and the rod is replaced withanother rod or other longitudinal connecting member or member component,such as one of the sleeves shown in FIGS. 52-72. Such locked positionmay also be released by the surgeon if desired with insert engagingtools (not shown). As will be described in greater detail below withrespect to the alternative insert 214 shown in FIGS. 47-51, in someembodiments of the invention, the insert does not have the receiverinterference fit feature. The locking insert 14 as well as thenon-locking insert 214 are preferably made from a solid resilientmaterial, such as a stainless steel or titanium alloy, so that portionsof the insert may be grasped, pinched or pressed, if necessary, andun-wedged from the receiver 10 with a release tool (not shown).

The locking compression insert 14 includes a body 156 with cylindricalsurfaces of a variety of diameters, the body 156 being integral with apair of upstanding arms 157. Located between the arms 157, the body 156has an outer substantially cylindrical surface 158. Located beneath eachupstanding arm 157 is a discontinuous, cylindrical, interference fitsurface 159 that extends outwardly from an arm and body outersubstantially cylindrical surface 160, a diameter of the surface 159being larger than a diameter of the surface 160. Beneath each surface159 is a discontinuous cylindrical surface 161 having a diameter thesame or similar to the surface 160. A frusto-conical or curvedtransition surface or ledge 162 spans between each surface 159 and thecorresponding lower cylindrical surface 161. The lower surface 161 isalso adjacent a substantially planar and annular bottom surface 164. Theinsert 14 further includes substantially planar arm top surfaces 165located opposite the bottom surface 164. A rectangularly shaped,substantially centrally located tool receiving aperture 167 is formed ineach arm surface 160 near each top surface 165, the aperture 167extending completely through the respective arm 157. The throughapertures 167 located directly across from one another advantageouslyallow for grasping the insert 14 with a tool either at the outsidesurfaces 160 or the inside surfaces of the arms 157. Located directlybelow each aperture 167 is a shallow aperture 168, also locatedcentrally on the arm surface 160, the aperture 168 also being adjacentthe interference fit surface 159. The apertures 168 are substantiallysquare in profile and do not extend entirely through the arm surface160. Running from each aperture 168 is a groove 170, sized and shaped toreceive and slidingly engage a receiver holding tab 78 during assemblyof the insert 14 with the receiver 10 when the insert 14 is rotated intoplace, as shown, for example, in FIGS. 29 and 30, the aperture 168ultimately capturing a respective tab 78 as will be described in greaterdetail below.

Turning to the inner surfaces of the insert 15, a through bore,generally 171, is disposed primarily within and through the body 156 andcommunicates with a generally U-shaped through channel formed by asaddle surface 173 that is substantially defined by the upstanding arms157. Near the top surfaces 165, the saddle surface 173 is substantiallyplanar, with the through apertures 167 extending therethrough. Thesaddle 173 has a lower seat 174 sized and shaped to closely, snuglyengage the rod 21 or other longitudinal connecting member. It isforeseen that an alternative embodiment may be configured to includeplanar holding surfaces that closely hold a square or rectangular bar aswell as hold a cylindrical rod-shaped, cord, or sleeved cordlongitudinal connecting member. The arms 157 disposed on either side ofthe channel extend upwardly and outwardly from the body 156 andterminate at the top surfaces 165. The arms 157 are sized and configuredfor ultimate placement beneath the receive guide and advancementstructure 72. It is foreseen that in some embodiments of the invention,the arms may be extended upwardly and the closure top configured suchthat the arms and, more specifically, the surfaces 165 ultimatelydirectly engage the closure top 18 for locking of the polyaxialmechanism, for example, when the rod 21 is made from a deformablematerial. In such embodiments, the insert 14 may include an additionalrotation blocking structure or feature that abuts against cooperatingstructure located on an inner wall of the receiver 10, preventingrotation of the insert with respect to the receiver when the closure topis rotated into engagement with the insert. In the illustratedembodiment, the surfaces 165 are ultimately positioned in spacedrelation with the closure top 18, so that the closure top 18frictionally engages the rod 21 only, pressing the rod 21 downwardlyagainst the seating surface 174, the insert 14 in turn pressing againstthe shank 4 upper portion 8 that presses against the retainer 12 to lockthe polyaxial mechanism of the bone screw assembly 1 at a desired angle.

The bore, generally 171, is substantially defined at the body 156 by aninner cylindrical surface 176 that communicates with the seat 174 and alower concave substantially radiused or partially spherical surface 178having a radius the same or substantially similar to a radius of thesurface 34 of the shank upper portion 8. The surface 178 terminates atthe base surface 164. Located between the cylindrical surface 176 andthe radiused surface 178 or located along the radiused surface 178 is ashank gripping surface portion, generally 180. The gripping surfaceportion 180 includes one or more stepped surfaces or ridges sized andshaped to grip and penetrate into the shank head 8 when the insert 14 islocked against the head surface 34. It is foreseen that the steppedsurface portion 180 may include greater or fewer number of steppedsurfaces. It is foreseen that the shank gripping surface portion 180 andalso the spherical surface 178 may additionally or alternatively includea roughened or textured surface or surface finish, or may be scored,knurled, or the like, for enhancing frictional engagement with the shankupper portion 8.

The compression insert 14 through bore 171 is sized and shaped toreceive a driving tool (not shown) therethrough that engages the shankdrive feature 46 when the shank body 6 is driven into bone with thereceiver 10 attached. Also, in some locking embodiments of theinvention, the bore receives a manipulation tool (not shown) used forreleasing the insert from a locked position with the receiver, the toolpressing down on the shank and also gripping the insert at the throughbores 167 located in the arms or with other tool engaging features. Forexample, a manipulation tool for releasing the insert from the receiver10 may also access such bores 167 from the receiver through theapertures 77 in the receiver. Thereby, tools can be configured torelease a locking insert from the inside and outside of the receiver 10.Each of the arms 157 and the insert body 156 may include more surfacefeatures, such as cut-outs notches, bevels, etc. to provide adequateclearance for inserting the insert 14 into the receiver and cooperatingwith the retainer 12 during the different assembly steps as will bedescribed in greater detail below.

The insert body 156 cylindrical surface 158 has a diameter slightlysmaller than a diameter between crests of the guide and advancementstructure 72 of the receiver 10, allowing for top loading of thecompression insert 14 into the receiver opening 66, with the arms 157 ofthe insert 14 being located between the receiver arms 62 duringinsertion of the insert 14 into the receiver 10. Once the arms 157 ofthe insert 14 are generally located beneath the guide and advancementstructure 72, the insert 14 is rotated in a clockwise direction intoplace about the receiver axis B until the receiver holding tabs 78 arelocated in the apertures 168 as will be described in greater detailbelow.

With reference to FIGS. 1 and 36-37, the illustrated elongate rod orlongitudinal connecting member 21 (of which only a portion has beenshown) can be any of a variety of implants utilized in reconstructivespinal surgery, but is typically a cylindrical, elongate structurehaving the outer substantially smooth, cylindrical surface 22 of uniformdiameter. The rod 21 may be made from a variety of metals, metal alloys,non-metals and deformable and less compressible plastics, including, butnot limited to rods made of elastomeric, polyetheretherketone (PEEK) andother types of materials, such as polycarbonate urethanes (PCU) andpolyethelenes.

Longitudinal connecting members for use with the assembly 1 may take avariety of shapes, including but not limited to rods or bars of oval,rectangular or other curved or polygonal cross-section. The shape of theinsert 14 may be modified so as to closely hold the particularlongitudinal connecting member used in the assembly 1. Some embodimentsof the assembly 1 may also be used with a tensioned cord as will bedescribed in greater detail with reference to FIGS. 52-74. Such a cordmay be made from a variety of materials, including polyester or otherplastic fibers, strands or threads, such as polyethylene-terephthalate.Furthermore, the longitudinal connector may be a component of a longeroverall dynamic stabilization connecting member, with cylindrical orbar-shaped portions sized and shaped for being received by thecompression insert 14 of the receiver having a U-shaped, rectangular- orother-shaped channel, for closely receiving the longitudinal connectingmember. The longitudinal connecting member may be integral or otherwisefixed to a bendable or damping component that is sized and shaped to belocated between adjacent pairs of bone screw assemblies 1, for example.A damping component or bumper may be attached to the longitudinalconnecting member at one or both sides of the bone screw assembly 1. Arod or bar (or rod or bar component) of a longitudinal connecting membermay be made of a variety of materials ranging from deformable plasticsto hard metals, depending upon the desired application. Thus, bars androds of the invention may be made of materials including, but notlimited to metal and metal alloys including but not limited to stainlesssteel, titanium, titanium alloys and cobalt chrome; or other suitablematerials, including plastic polymers such as polyetheretherketone(PEEK), ultra-high-molecular weight-polyethylene (UHMWP), polyurethanesand composites, including composites containing carbon fiber, natural orsynthetic elastomers such as polyisoprene (natural rubber), andsynthetic polymers, copolymers, and thermoplastic elastomers, forexample, polyurethane elastomers such as polycarbonate-urethaneelastomers.

With reference to FIGS. 1 and 36-37, the closure structure or closuretop 18 shown with the assembly 1 is rotatably received between thespaced arms 62 of the receiver 10. It is noted that the closure 18 topcould be a twist-in or slide-in closure structure. The illustratedclosure structure 18 is substantially cylindrical and includes a anouter helically wound guide and advancement structure 182 in the form ofa flange that operably joins with the guide and advancement structure 72disposed on the arms 62 of the receiver 10. The flange form utilized inaccordance with the present invention may take a variety of forms,including those described in Applicant's U.S. Pat. No. 6,726,689, whichis incorporated herein by reference. Although it is foreseen that theclosure structure guide and advancement structure could alternatively bea buttress thread, a square thread, a reverse angle thread or otherthread like or non-thread like helically wound advancement structure,for operably guiding under rotation and advancing the closure structure18 downward between the arms 62 and having such a nature as to resistsplaying of the arms 62 when the closure structure 18 is advanced intothe channel 64, the flange form illustrated herein as described morefully in Applicant's U.S. Pat. No. 6,726,689 is preferred as the addedstrength provided by such flange form beneficially cooperates with andcounters any reduction in strength caused by the any reduced profile ofthe receiver 10 that may more advantageously engage longitudinalconnecting member components. The illustrated closure structure 18 alsoincludes a top surface 184 with an internal drive 186 in the form of anaperture that is illustrated as a hex drive, or may be, for example, astar-shaped internal drive such as that sold under the trademark TORX orother internal drives such as slotted, tri-wing, spanner, two or moreapertures of various shapes, and the like. A driving tool (not shown)sized and shaped for engagement with the internal drive 186 is used forboth rotatable engagement and, if needed, disengagement of the closure18 from the receiver arms 62. It is also foreseen that the closurestructure 18 may alternatively include a break-off head designed toallow such a head to break from a base of the closure at a preselectedtorque, for example, 70 to 140 inch pounds. Such a closure structurewould also include a base having an internal drive to be used forclosure removal. A base or bottom surface 188 of the closure is planarand further includes a point 189 and a rim 190 for engagement andpenetration into the surface 22 of the rod 21 in certain embodiments ofthe invention. It is noted that in some embodiments, the closure topbottom surface 188 does not include the point and/or the rim. Theclosure top 18 may further include a cannulation through bore (notshown) extending along a central axis thereof and through the top andbottom surfaces thereof. Such a through bore provides a passage throughthe closure 18 interior for a length of wire (not shown) insertedtherein to provide a guide for insertion of the closure top into thereceiver arms 62. An alternative closure top, such as the top 18′ shownin FIGS. 39 and 40 for use with a deformable rod, such as a PEEK rod21′, for example, includes a bottom surface 188′ that has domed portion190′ with a central nub 189′ in lieu of the point and rim surface of theclosure top 18. Otherwise, the closure top 18′ includes a guide andadvancement structure 182′, a top surface 184′ and an internal drivefeature 186′ the same or substantially similar to the respective guideand advancement structure 182, top surface 184 and internal drivefeature 186 of the closure top 18.

The assembly 1 receiver 10, retainer 12 and compression insert 14 aretypically assembled at a factory setting that includes tooling forholding and alignment of the component pieces and manipulating theretainer 12 and the insert 14 with respect to the receiver 10. In somecircumstances, the shank 4 is also assembled with the receiver 10, theretainer 12 and the compression insert 14 at the factory. In otherinstances, it is desirable to first implant the shank 4, followed byaddition of the pre-assembled receiver, retainer and compression insertat the insertion point. In this way, the surgeon may advantageously andmore easily implant and manipulate the shanks 4, distract or compressthe vertebrae with the shanks and work around the shank upper portionsor heads without the cooperating receivers being in the way. In otherinstances, it is desirable for the surgical staff to pre-assemble ashank of a desired size and/or variety (e.g., surface treatment ofroughening the upper portion 8 and/or hydroxyapatite on the shank 6),with the receiver, retainer and compression insert. Allowing the surgeonto choose the appropriately sized or treated shank 4 advantageouslyreduces inventory requirements, thus reducing overall cost and improvinglogistics and distribution.

Pre-assembly of the receiver 10, retainer 12 and compression insert 14is shown in FIGS. 24-30. With particular reference to FIG. 24, first theretainer 12 is inserted into the upper receiver opening 66, leading withthe outer panels 118 with the panel 118 top surfaces 134 facing one arm62 and the retainer bottom surface 122 facing the opposing arm 62 (shownin phantom). The retainer 12 is then lowered in such sideways mannerinto the channel 64 and partially into the receiver cavity 61, followedby tilting the retainer 12 such that at least one panel top surface 134is located beneath the surface 85 of one of the receiver holding tabs 78and the opposed holding tab 78 is located generally between a pair ofpanels 118, for example, at or near the retainer slit 148 as shown insolid lines in FIG. 24. Then, with reference to FIG. 25, the retainer 12is tilted into a position wherein the central axis of the retainer 12 isgenerally aligned with the receiver central axis B and the receiverholding tabs 78 are each located between pairs of adjacent panels 118and extend over retainer body top surfaces 126 located opposite oneanother, with each tab surface 85 being located directly above a topsurface 126 or the slit 148. FIG. 26 shows a bottom plan view of thereceiver and retainer at the intermediate stage of assembly shown inFIG. 25, illustrating how the cut-out portion 149 of the retainer 12 islocated generally inward of the inner surfaces making up the receivercavity 61. FIGS. 25 and 26 also illustrate the retainer 12 at acompressed state with the slit surfaces 152 and 153 being at a neartouching state so that the cylindrical surfaces 120 slide past thereceiver inner surface 95.

With reference to FIGS. 27 and 28, after the panels 118 are locatedbetween holding tabs 78, the retainer 12 is lowered into the receivercavity 61 with the resilient panels 118 being pressed inwardly, usingtooling, or by the use of a downward force that results in compressionof the panels 118 toward the axis B due to engagement with the receiversurfaces 95. It is noted that the retainer 12 shown in FIG. 27, has beenrotated about the receiver axis B from the position shown in FIG. 25.Such rotation is not required prior to downloading the retainer into thereceiver cavity 61, but has been illustrated here to provide the readerwith a cross-sectional view of the retainer 12 that more clearly showsthe position and orientation of the retainer panels 117 and 118 withrespect to the receiver cavity surfaces. With further reference to FIG.28, the retainer 12 is pressed downwardly until the retainer is in adesired temporary position within the receiver 10 with panel 118 outersurfaces 132 engaging the receiver inner surfaces 95, thereby holdingthe retainer 12 within the receiver at such location during loading andinitial assembly of the insert 14 into the receiver 10. At this time,the retainer 12 is not yet fully captured within the receiver basecavity 61, but cannot be readily removed unless the panels 118 aresqueezed toward one another using a tool or tools.

With reference to FIGS. 29-31, the compression insert 14 is thendownloaded into the receiver 10 through the upper opening 66 with thebottom surface 164 facing the receiver arm top surfaces 73 and theinsert arm outer surfaces 160 located between the opposed receiver arms62. The insert 14 is then lowered toward the receiver base 60 until theinsert 14 arm upper surfaces 165 are adjacent the run-out area below theguide and advancement structure 72 defined in part by the cylindricalsurface 92. Thereafter, the insert 14 is rotated (see the arrow K inFIG. 30) about the receiver axis B until the upper arm surfaces 165 aredirectly below the guide and advancement structure 72 with the U-shapedchannel 173 of the insert 14 aligned with the U-shaped channel 64 of thereceiver 10. In some embodiments, the insert arms may need to becompressed slightly during rotation to clear some of the inner surfaces70 of the receiver arms 62. With particular reference to FIGS. 30 and31, as the insert 14 is rotated about the axis B, the receiver holdingtab surfaces 84 slide along the insert groove surfaces 170 and then arecaptured with the insert apertures 168. The insert apertures 168 helpretain the desired alignment between the insert 14 and the receiver 10and prohibit relative rotation between the two parts. However, relativevertical movement between the insert 14 and the receiver 10 is possibleas the apertures 168 do not vertically fix the insert with respect tothe receiver. At this time also, the insert bottom surface 164 isresting on the top surfaces 134 of the panels 118. However, thefrictional engagement between the panels 118 and the receiver innersurfaces 95 prohibit the retainer 12 and thus also the insert 14 fromdropping further down into the receiver 10 cavity 61. The retainer 12and the insert 14 are now in a desired position for shipping as anassembly along with the separate shank 4. The insert 14 is also fullycaptured within the receiver 10 by the guide and advancement structure72 prohibiting movement of the insert 14 up and out through the receiveropening 66 as well as by retainer 12 located below the insert.

Typically, the receiver and retainer combination are shipped orotherwise provided to the end user with the spring-like panels 118wedged against the receiver as shown in FIG. 31. The receiver 10,retainer 12 and insert 14 combination is now pre-assembled and ready forassembly with the shank 4 either at the factory, by surgery staff priorto implantation, or directly upon an implanted shank 4 as will bedescribed herein.

As illustrated in FIG. 31, the bone screw shank 4 or an entire assembly1 made up of the assembled shank 4, receiver 10, retainer 12 andcompression insert 14, is screwed into a bone, such as the vertebra 17(shown in phantom), by rotation of the shank 4 using a suitable drivingtool (not shown) that operably drives and rotates the shank body 6 byengagement thereof at the internal drive 46. Specifically, the vertebra17 may be pre-drilled to minimize stressing the bone and have a guidewire (not shown) inserted therein to provide a guide for the placementand angle of the shank 4 with respect to the vertebra. A further taphole may be made using a tap with the guide wire as a guide. Then, thebone screw shank 4 or the entire assembly 1 is threaded onto the guidewire utilizing the cannulation bore 50 by first threading the wire intothe opening at the bottom 28 and then out of the top opening at thedrive feature 46. The shank 4 is then driven into the vertebra using thewire as a placement guide. It is foreseen that the shank and other bonescrew assembly parts, the rod 21 (also having a central lumen in someembodiments) and the closure top 18 (also with a central bore) can beinserted in a percutaneous or minimally invasive surgical manner,utilizing guide wires and attachable tower tools mating with thereceiver. When the shank 4 is driven into the vertebra 17 without theremainder of the assembly 1, the shank 4 may either be driven to adesired final location or may be driven to a location slightly above orproud to provide for ease in assembly with the pre-assembled receiver,compression insert and retainer.

With reference to FIG. 32, the pre-assembled receiver, insert andretainer are placed above the shank upper portion 8 until the shankupper portion is received within the opening 110. With particularreference to FIGS. 32-35, as the shank upper portion 8 is moved into theinterior 61 of the receiver base, the shank upper portion 8 pressesupwardly against the retainer 12 in the receiver recess partiallydefined by the cylindrical surface 98. As the shank head 8 continues tomove upwardly toward the channel 64, the shank head surface 34 forcesthe retainer 12 against the insert 14. However, the insert 14 isprohibited from moving upward by the receiver guide and advancementstructure 72. Therefore, the upwardly moving shank head 8 forces awidening of the retainer slit 148 and corresponding outward movement ofthe body 115 of the retainer 12 towards the receiver cylindricalsurfaces 98 and 100 defining the receiver expansion recess or chamber asbest shown in FIG. 33, while the retainer panels 118 near the topsurfaces 134 thereof are generally maintained in a location directlybelow the insert 14 bottom surface 164. At this time, the sphericalsurface 34 of the head 8 comes into contact with the retainer innercylindrical body 145 and the edge 147. With reference to FIG. 34. Withreference to FIG. 34, the retainer 12 begins to return towards a neutralor nominal state as the center of the sphere of the shank head 8 passesbeyond the retainer surface 147. By the time the hemisphere of thespherical surface 34 extends into a desired captured location within theretainer central channel 141, the shank surface 34 is in contact withthe edge 147 as well as with the inner panels 117 at surfaces 129. Thecombination of the rim or edge 147 surface contact and the panel 117surfaces 129 contact resiliently pressing against the radiused surface34, provides a fairly tight friction fit between the head 8 and theretainer 12, the surface 34 being pivotable with respect to the retainer12 with some force. Thus, a tight, non-floppy ball and socket joint isnow created between the retainer 12 and the shank upper portion 8.

With reference to FIG. 35, the receiver is then pulled upwardly or theshank 4 and attached retainer 12 are then moved manually downwardly intoa position wherein the retainer panels 118 are disengaged from thereceiver surfaces 95, allowing the panels 118 to resiliently release andextend outwardly into a neutral or near-neutral position at a locationbelow the receiver annular surface 96 that defines the ceiling of thereceiver inner chamber 61. The panels 118 are now captured within thereceiver and the retainer with any upward movement resulting in thepanel top surfaces 134 abutting against the receiver surfaces 96 and/or97. However, although fully capture, the retainer/shank combination isadvantageously only partially restrained with respect to the receiver,as a user is able to rotate the retainer about the receiver axis B priorto locking of the shank with respect to the receiver. At this time also,the retainer surface 121 and bottom surface 122 that forms a lower skirtbeneath the retainer body surfaces 120 and 124 are all seated within thestepped surfaces of the receiver. Specifically, the retainer lowersurfaces 124 are seated on the receiver annular surface 102 and thebottom surface 122 is seated on the annular surface 103. Downwardpressure of the shank head 8 on the retainer edge 147 further expandsthe retainer body 115 outwardly, with the outer surfaces 120 pressingagainst the receiver inner cylindrical surface 100 and the lower skirtsurface 121 pressing against the receiver inner cylindrical surface 101.The retainer body formed in part by the lower skirt surface 121advantageously allows for the head 8 to seat lower within the receiverthan in other known polyaxial bone anchors. As will be described ingreater detail below, the skirt feature that allows for a more stablelower seating surface in combination with the retainer cupped surface149 that allows for increased angular orientation of the shank withrespect to the retainer, and thus with respect to the entire bone screwassembly, allows for such an angular increase without the need toprovide a cut-out or cupped surface at and near the receiver bottom 108.Also advantageous is the fact that the partially constrained retainer 12may be rotated with respect to the receiver 10 about the axis B,allowing for the user to choose the location of the increased angle oforientation between the receiver 10 and the shank 4.

With further reference to FIG. 35, after the retainer 12 is moveddownwardly into the receiver 10 and seated on the surfaces 102 and 103,the insert 14 remains located spaced above the shank head 8 as thereceiver spring tabs 78 and/or the receiver stepped surface 94 prohibitsdownward movement of the insert 14 unless a downward force is applied onthe insert either by a tool or the rod 21 and closure top 18 shown inFIG. 36, for example. In some embodiments, when the receiver 10 ispre-assembled with the shank 4, the entire assembly 1 may be implantedat this time by inserting the driving tool (not shown) into the receiverand the shank drive 46 and rotating and driving the shank 4 into adesired location of the vertebra 17. At this time, prior to locking witha closure top, the receiver 10 may be articulated to a desired angularposition with respect to the shank 4 (such as the angular orientationsshown in FIGS. 41 and 43, for example), that will be held, but notlocked, by the frictional engagement between the retainer 12 innerpanels 117 and the shank upper portion 8. In some cases it may bedesirable to lock the insert 14 into the receiver 10 at this time, theinsert 14 being pressed downwardly into locking engagement with theshank head 8 by a tool pressing downwardly on the insert, the toolentering through the receiver opening 66 and pressing downwardly on theinsert saddle 153. Such a tool may also include (or alternatively be) astructure for gripping the receiver, for example, a pronged tool or toolportion extending into the receiver apertures 77. Or, as explainedabove, the insert 14 may remain spaced above the shank head 8 untillocked into place by the rod 21 and the closure top 18 pressing downupon the insert 14. As explained above and as best shown in FIGS. 37 and38, the diameter of the insert outer surface 159 is sized large enoughto require that the surface 159 must be forced into the cylindricalsurface 95 of the receiver by a tool or tools or by the closure top 18forcing the rod 21 downwardly against the insert 14 with sufficientforce to interferingly frictionally lock or wedge the insert 14 into thereceiver 10 at the surface 159. This independent lock-and-releasefeature gives the surgeon flexibility to loosen the closure top and evenremove the closure top and rod without affecting the locking of thepolyaxial mechanism of the assembly 1, the anchor assembly functioninglike a fixed monoaxial screw with the shank 4 in fixed relation with thereceiver 10, but with the shank remaining in a desired angle withrespect to the receiver. For example, with reference to FIGS. 39 and 40,once the insert 214 is locked against the receiver as shown in FIG. 38,if a rod and closure top have been assembled with the receiver 10, theclosure top 18 may be loosened or removed and/or the rod 21 may beadjusted and/or removed and the frictional engagement between the insert14 and the receiver 10 at the receiver surface 95 will remain locked inplace, advantageously maintaining a locked angular position of the shank4 with respect to the receiver 10. At such time, another rod, such as adeformable rod 21′ and cooperating alternative closure top 18′ may beloaded onto the already locked-up assembly to result in an alternativeassembly. The illustrated rod 21′ has the same dimensions as the rod 21,with a cylindrical surface 22′, but is made from a material, such asPEEK, that deforms in response to pressure from the closure top, thusmaking the closure top 18′ having the domed surface 190′ and central nub189′ a more desirable locking mechanism for keeping the deformable rod18′ in place within the receiver 10. Because the locking of thepolyaxial mechanism of the assembly is not dependent on the force of therod 21′ and closure top 18′ on the insert 14, any further deformation oreventual loosening of the rod with respect to the closure top 18′ or theinsert 14 does not affect the secure locking between the insert 14 andthe receiver 10 and thus the shank 4 stays frictionally locked againstboth the insert 14 and the retainer 12, locking the shank 4 in a desiredangular position with respect to the receiver 10.

If unlocking of the insert 14 with respect to the receiver 10 isdesired, a tool (not shown) may be inserted into the through apertures77 of the receiver 10 and the through apertures 167 of the insert 14 andthe insert 14 may be pulled away from the receiver 10. Such a tool mayinclude a piston-like portion for pushing directly on the shank whilethe insert 14 is pulled away from the receiver. At such time, the shank4 may be articulated with respect to the receiver 10, and the desiredfriction fit returns between the retainer 12 and the shank surface 34,so that an adjustable, but non-floppy relationship still exists betweenthe shank 4 and the receiver 10. If further disassembly if the assemblyis desired, such is accomplished in reverse order to the proceduredescribed previously herein for the assembly 1.

Returning to FIGS. 36-38, the rod 21 is positioned in an open orpercutaneous manner in cooperation with the at least two bone screwassemblies 1. The closure structure 18 is then advanced between the arms62 of each of the receivers 10. The closure structure 18 is rotated,using a tool engaged with the inner drive 186 until a selected pressureis reached at which point the rod 21 engages the U-shaped saddle 173 ofthe compression insert 14, further pressing the insert spherical surface178 and stepped shank gripping surfaces 180 against the shank sphericalsurface 34, the edges of the stepped surfaces 180 penetrating into thespherical surface 34, pressing the shank upper portion 8 into lockedfrictional engagement with the retainer 12. Specifically, as the closurestructure 18 rotates and moves downwardly into the respective receiver10, the point 189 and rim 190 engage and penetrate the rod surface 22,the closure structure 18 pressing downwardly against and biasing the rod21 into compressive engagement with the insert 14 that urges the shankupper portion 8 toward the retainer 12 and into locking engagementtherewith at the retainer edge surface 147, the retainer 12 frictionallyabutting the receiver surfaces 102 and 103 and pressing outwardlyagainst the receiver cylindrical surfaces 100 and 101. For example,about 80 to about 120 inch pounds of torque on the closure top may beapplied for fixing the bone screw shank 6 with respect to the receiver10. At this time, the retainer inner edge 147 engages and digs into theshank head 8. At this time, the inner panels 117 may be slightly spacedfrom the shank head 8 or may be still touching the shank sphericalsurface 34, but are no longer in tight or close frictional engagementwith the surface 34 and thus are not participating in the final lockingengagement between the shank 4 and the retainer 12. As best shown inFIG. 38, due to the position and geometry of the lower skirt surfaces121 and 122 with respect to the receiver 10 and also due to the locationof the inner edge 147, the shank head 8 sits low in the receiver cavity61, allowing for desirable increased articulation of the shank 4 withrespect to the retainer 12 and thus with respect to the receiver 10 ascompared to a retainer that does not include such a lower skirt, forexample. If disassembly if the assembly 1 is desired, such isaccomplished in reverse order to the procedure described previouslyherein for assembly.

With reference to FIGS. 41-46, different angular or articulatedpositions of the shank 4 with respect to the receiver 10 are shown, somemaking full use of the slit 148 and adjacent cut-out or cupped surfaces149 of the retainer 12. For example, compare FIGS. 43-45 wherein theshank 8 is pivoted toward and into engagement with the cupped surfaces149 as compared to the arrangement shown in FIGS. 41 and 42, wherein theshank 4 is pivoted in a direction opposite to the retainer slit 148. InFIGS. 41 and 42 wherein the shank is pivoted in a direction away fromthe slit 148 and cupped surfaces 149, a resulting shank to receiverarticulation is about twenty-two degrees (cephalad, for example), whichis a desirable degree of articulation in some instances. FIGS. 43-46show a thirty-three (caudad) or slightly further articulation, possiblewhen the shank head 8 abuts against both surfaces 149 as well as movingslightly into the gap formed by the slit 148.

FIG. 46 illustrates an alternative receiver 10′ that includes a bottomsurface 108′ further defined by a pair of opposed, stepped and concavecurved bottom surfaces 109′. Otherwise, the receiver 10′ is identical tothe receiver 10 described above and thus fully cooperates with theretainer 12, insert 14, shank 4, rod 21 and closure top 18 in a mannersubstantially identical to what has been described above with respect tothe assembly 1. Just like the receiver 10, when the retainer 12 is fullyassembled with the receiver 10′, the retainer 12 is captured within thereceiver inner cavity 61′, but is only partially constrained therein,the retainer being rotatable about the central axis of the receiver 10′.Thus, the retainer 12 slit 148 and surfaces 149 can be aligned witheither of the receiver stepped surfaces 109′. When the retainer surfaces149 are aligned one of the surfaces 109′, at least a forty degree angleof articulation between the shank 4 and the receiver 10′ is possible.

With reference to FIGS. 47-51, an alternative non locking compressioninsert 214 is illustrated for use with the shank 4, receiver 10,retainer 12, closure top 18 and rod 21 previously described herein. Theinsert 214 is substantially similar to the insert 14 previouslydescribed herein, having all the features of the insert 14 with theexception of the through apertures 167 and the enlarged interference fitsurface 159. Instead, the insert includes a pair of opposed alternativeapertures 166 formed into arm surfaces that do not extend all the waythrough the insert arms and a cylindrical surface 259 that is similar tothe surface 159 of the insert 14, except that a diameter of the surface259 is sized to easily slidingly fit within the receiver surface 95rather than interferingly fit with such surface. Thus, the insert 214includes an insert body 256, a pair of upstanding arms 257, acylindrical body surface 258, arm outer surfaces 260, a lowercylindrical surface 261 a sloping ledge 262, a planar bottom 264, armtops 267, grooves 270, a central through bore 271, a saddle surface 273,a saddle seat 274, an inner cylindrical surface 276, a lower radiusedsurface 278 and a shank gripping portion 280, as well as other featuresthat are the same as, or substantially similar to, the respective insertbody 156, pair of upstanding arms 157, cylindrical body surface 158, armouter surfaces 160, lower cylindrical surface 161 sloping ledge 162,planar bottom 164, arm tops 167, grooves 170, central through bore 171,saddle surface 173, saddle seat 174, inner cylindrical surface 176,lower radiused surface 178 and shank gripping portion 180 of the insert14 previously described herein.

Each insert aperture 266 is a depression formed in the surface 260having a substantially rectangular profile similar to the aperture 168of the insert 14. Also, each aperture 266 opens toward and communicateswith the respective adjacent groove 270 for assembly with the receiverholding tab 78 in a manner similar to the cooperation previouslydescribed herein between the aperture 168 and the groove 170 of theinsert 14. However, unlike the smooth substantially planar surfacedefining each aperture 168, each aperture 266 further includes ahorizontal bar or bridge portion 267 substantially parallel to the topsurface 265 that separates the aperture 266 into two portions; an upperportion 268 and a lower portion 269, each having a substantially planarsurface for sliding cooperation with a holding tab surface 84. Duringassembly with the receiver, the insert 214 is rotated and the receiverholding tab surfaces 84 slide along the grooves 270 until they springinto the apertures 266 at the lower portions 269 thereof, each bar 267abutting against each tab 78 at the top surface 82, prohibiting theinsert 214 from moving further downwardly into the receiver cavity 61.Thus, unlike the insert 14 that cannot move further into the cavitybecause of the interference fit surface 159, the insert bars 267 capturethe tabs 78 in the lower portion 269 of each aperture 266 duringassembly, and shipping, if desired, keeping the insert 214 in adesirable position until the insert 214 is pressed, with some force,either by a tool or by the rod 21 and closure top 18 in a downwarddirection, the tabs 78 resiliently sliding along lower sloping surfacesof the bars 267 until the tabs 78 slide past the bars 267 and the tabsurfaces 84 spring into the upper aperture portions 268, as shown, forexample, in FIG. 51.

The insert is otherwise assembled with the receiver 10, retainer 12,shank 4, rod 21 and closure top 18 in a manner the same as previouslydescribed above with respect to the assembly 1, with the exception thatthe insert 214 need not be forced downwardly into a locking interferencefit with the receiver 10 when the shank 4 is locked in place. If theclosure top 18 is loosened or if the closure top 18 and the rod 21 areremoved from the assembly 1, the insert 214 will also shift upwardly inthe receiver 10 and the shank 4 will not remain locked with respect tothe retainer 12 and the receiver 10.

With reference to FIGS. 52-74, polyaxial bone screw assemblies 1 (aswell as alternative bone screw assemblies 1001 and 2001 described below)according to the invention may be used with longitudinal connectingmember assemblies that are sometimes called “soft” or “dynamic”connectors that may include one or more sleeves with cooperating,spacers, bumpers, an inner tensioned cord, and may include one or twoend blockers or fixers for fixing the cord to the connector assembly. Avariety of such connector components are described in Applicant's U.S.patent application Ser. No. 12/802,849 filed Jun. 15, 2010 (U.S.Publication No. 2010/0331887) and incorporated by reference herein. Withreference to FIG. 57, the bone screw 1 is illustrated assembled with ahard, inelastic, flanged sleeve 304, through which a tensioned cord 306extends, sleeve and cord may be a part of such a longitudinal connectorassembly or system as described in U.S. patent application Ser. No.12/802,849. The sleeve 304 is also illustrated in greater detail inFIGS. 52-56, for example. Another alternative sleeve 305 is shownassembled with the bone screw assembly 1 in FIG. 64. The sleeve 305 isshown in greater detail in FIGS. 66-70. The cord 306, is shown, forexample, in FIGS. 57-59 and 61-63.

With particular reference to the sleeve 304 shown in FIGS. 52-63, thereis further illustrated at FIGS. 62 and 63 a cooperating end cord blockeror fixer 310 with a cord fixing set screw 312, an elastic end bumper 314and a substantially cylindrical spacer 316 that may be elastic orinelastic. The cylindrical, tubular spacer 316 includes an outer annulargroove near an end thereof, aiding in elastic compression. However, inother embodiments, the spacers may not have grooves. Spacers may be cutto a desired length on the end opposite the groove. The cord blocker310, the bumper 314 and spacer 316 are each located about the cord 306,typically with spacers 316 being disposed between each pair of boneanchors 1 of an overall assembly (not shown) that includes at least twobone anchors 1, but may include any number of bone anchors with the cord306 at least fixed at either end, either at a terminal or end boneanchor 1 or at an end blocker 310 or other fixing member that may be,for example, a cord to hard rod coupler. The tubular bumper 314 andtubular spacers 316 shown in the figures are transparent, allowing forviewing of the sleeve 304 and the tensioned cord 306. However, it isforeseen that in other embodiments, the bumper and spacers may be madeof materials that may not be transparent or translucent. Also as shownin FIGS. 60 and 61, two types of bone screw closures are utilized,either a slide or slipping closure top 18 previously described hereinwith respect to the assembly 1 or a cord gripping closure top 18″. Theclosure top 18″ is also illustrated in FIGS. 65 and 66 and only differsfrom the top 18 in that the top 18″ does not include a bottom rim orbottom point, but rather a cord fixing or penetrating extension 317having a bottom surface 318 for gripping the cord 306. With reference toFIG. 58, the slide or slip closure top 18 engages a respective sleeve304 but not the cord 306, allowing the cord to slip or slide within thepolyaxial screw 1. With reference to FIG. 61, the grip closure top 18″extends through the sleeve 304 at the bore 360 and the surface 318 gripsand fixes the cord 306 against an inner surface defining the bore 336 ofthe sleeve 304 and thus fixes the cord 306 in relation to the polyaxialscrew 1 that is mated with the closure top 18″.

Although not shown, the sleeve 304 and cord blocker 310 may includetubular extensions at either side thereof that may be sized and shapedto extend into the inner lumen or bore of the spacers 316 or the bumper314. Such spacer overlap with respect to the sleeves is sometimesdesired to provide additional anti-shear support for a connectingmember. The bumper 314 also extends about the cord 306 and is typicallymade from an elastomer while the outer spacers 316, although typicallyelastomeric, may be made from a material with a different durometer,typically (but not always) being tougher and less compressible than thematerial of the bumper 314. The sleeves 304 and in some embodiments thespacers 316 are typically made from a hard, non-elastic material, suchas a metal or metal alloy, like cobalt chromium. Flanged portions of thesleeves 304 are located on either side of the bone screw receivers 10,the flanges abutting directly against the spacers 316 or the bumper 314,the flanges extending radially outwardly to an extent to fully engageends of adjacent spacers or the bumper, resulting in a stable, secure,substantially full contact between the individual elements of aconnector assembly. Furthermore, the flanges allow for assembly anddynamic setting of a longitudinal connector prior to implantation of theconnector, if desired, with the cord 306 being placed in tension and atleast the bumper 314 being placed in compression. In some embodiments ofthe invention, tensioning of the cord 316 and compression of the bumper314 and optionally the spacers 316 may be performed after thelongitudinal connector assembly sleeves 304 (or 305) are attached to thebone screws 1.

With particular reference to FIG. 57, the bone screw assembly 1 isillustrated assembled with the sleeve 304. With particular reference toFIGS. 52-56, the sleeve 304 further includes a body portion 334generally sized and shaped for being received within the polyaxial bonescrew 1 receiver 10 and about a cord 306. A through bore 336 extendscentrally through the body portion 334, the bore 336 being sized andshaped to slidingly receive the cord 306. At either side of the bodyportion 334 are a pair of opposed spaced radially extending flanges 338.The body portion 334 includes an annular planar top surface 340, asubstantially cylindrical bottom surface 341, opposed planar surfaces342 adjacent the bottom surface 341 and opposed partially cylindrical orotherwise protruding portions 344 located above each surface 342. Thetop annular surface 340 partially defines each of the protrudingportions 344. The body 334 is sized and shaped to closely fit withininner arm surfaces of the bone screw receiver 10. The portions 344function to center the sleeve 304 within the bone screw receiver 10 andalso advantageously strengthen the sleeve, resulting in better loadtransfer. It is foreseen that in some embodiments, the flanges 338 maybe reduced or eliminated as the centering of the sleeve with respect tothe bone screw receiver 10 may be performed by the portion or portions344.

In the illustrated embodiment, each flange 338 has a substantiallycylindrical outer surface 346 adjacent and perpendicular to an outerplanar annular surface 348 that is sized and shaped for directlyabutting against a bumper or a spacer. The bore 336 extends through eachof the planar surfaces 348. The cylindrical surface 346 is truncated ata lower end thereof forming the bottom surface 350 that is also adjacentand substantially perpendicular to the surface 348. Variously curvedtransition surfaces 351 curve towards a more uniform flange 352 that islocated adjacent to the body lower cylindrical surface 341, the surfaces351 being sized and shaped to clear the receiver inset surfaces 63located near the receiver U-shaped seat 68 when the sleeve is insertedinto the receiver U-shaped channel 64 and seated on the seat 174 of theinsert 14. The body lower cylindrical surface 341 is sized and shaped tobe closely received by the insert saddle 173 near the receiver seat 68.Adjacent to the transition surfaces 351 and the cylindrical surfaces346, each flange includes inner opposed facing surfaces 353. Between thesurfaces 353 and the sleeve body 334 there are concave cupped surfaces355 that are sized and shaped to receive and partially wrap aboutportions of the receiver arm surfaces 71 that transition between innerand outer facing surfaces of the arms. The surfaces 353 also receive andcurve about portions of the receiver outer surfaces 76 located adjacentthe transition arm surfaces 71, see FIGS. 57 and 62, for example. Nearthe top body surface 340 and also adjacent to the outer cylindricalsurface 346 of the flange, the flanges also include inner cylindricalsurfaces 356, sized and shaped to provide clearance for receiving theclosure top 18 or 18″. It is noted that the body portion 334 as well asthe inner surfaces of the flanges 338 may be sized and shaped to bereceivable by and frictionally fixed to a variety of monoaxial orpolyaxial screw heads or receivers, including, but not limited to, thereceiver 10.

With reference to FIGS. 52, 54 and 56, a bore 360 is formed in the body334 at the top surface 340 and located centrally between the flanges338. The bore 360 is transverse to and communicates with the throughbore 336. The bore 360 is sized and shaped to receive the cordpenetrating extension 317 of the closure top 18″ therein as best shownin FIG. 61. The sleeve 304 is shown with the closure top 18 in FIGS.57-59. The top 18 does not extend down into the through bore 360,allowing for the cord 306 to slide freely there within.

The sleeve 304, as well as the cord blocker 310 with set screw 312 maybe made from a variety of inelastic materials, including, but notlimited to metals, metal alloys, including cobalt chromium, andinelastic plastics including, but not limited to plastic polymers suchas polyetheretherketone (PEEK), ultra-high-molecular weight-polyethylene(UHMWP), polyurethanes and composites, including composites containingcarbon fiber and layers of different materials.

With reference to FIG. 57 that shows the sleeve 304 assembled with thebone screw 1 and having a pair of cylindrical and tubular spacers 316 oneither side thereof, the sleeve and spacers surrounding a cord 306, andalso with respect to FIG. 62, that shows the sleeve 304 cooperating withboth a spacer 316 and a blocker 310 and bumper 312, as well as a cord306, a connecting member assembly utilizing the sleeve 304, cord 306,cord blocker 310, bumper 314 and one or more cylindrical spacers 316 maybe assembled as follows:

First, after two or more bone screws 1 are implanted, the distancebetween the screws is measured. Thereafter, the spacers 316 are cut to adesired length based upon the measurement made between the bone screws.Because the sleeves 304 are made from a hard material, typically a metalor metal alloy, if it is desired to use sleeves with tubular extensions,it is not practical to cut the tubular portions to a desired lengthduring the surgical procedure.Therefore, a variety of sleeves 304 are typically provided to end usershaving at least three different tube portion lengths. Thereafter, thesleeves 304, spacers 316, bumper 314 and a cord blocker 310, (or twocord blockers on either end, with or without an adjacent bumper) are fedonto a cord 306 in a desired order to result in a desired assembly in amanner described in greater detail in the patent application Ser. No.12/802,849 incorporated by reference herein. It is noted that the cord306 is typically much longer than shown in the drawing figures and thencut to length near an end thereof after being fully assembled with theremaining elements of the connector assembly, tensioned and fixed to theblocker 310. In some embodiments of the invention, single blockers,bumper/blocker combinations or rod/cord couplers (or various differentcombinations thereof) may be placed on either end of the assembly andthe cord pre-tensioned before the assembly is implanted in and betweenthe already implanted bone screws 1. In other embodiments, a looselyassembled connector may be placed in contact with and between theimplanted bone screws 1, with the set screw 312 engaged with the cord306 enough to prevent the elements from slipping off one end of the cord306. However, in such an assembly, the cord 306 would not yet betensioned and thus the individual elements would be spread apart alongthe cord and the cord would have to be of a length so that the cordcould be grasped and tensioned after the assembly is fixed to the bonescrews 1.

A connector member assembly is then implanted by inserting each sleeve304 into to one of the bone screws 1. The sleeve 304 is top loadedthrough the receiver opening 66 with the inner curved surfaces 355aligned with and sliding along the arm edge surfaces 71 until the sleeve304 is seated on the insert 14 with the sleeve protrusions 344 engagingthe insert arm top surfaces 165. Closure tops 18 or 18″ are theninserted into and advanced between the arms of the bone screw receiver10 so as to bias or push against the respective sleeves 304. A drivingtool (not shown) is inserted into each closure drive to rotate and drivethe respective closure top 18 or 18″ into the respective receiver 10,the lower surface of the closure top engaging and pressing downwardlyupon the top body surface 340 of the sleeve 304. As shown in FIG. 58,when the closure top 18 is used, the bottom rim 190 digs into the topbody surface 340 but the closure does not engage the cord 306 locatedwithin the sleeve bore 336. As shown in FIGS. 58 and 61, downwardmovement of the closure top 18 or 18″ onto the sleeve 304 in turnpresses the sleeve 304 into engagement with the insert 14 that in turnpresses downwardly on the shank head 8, locking the head 8 between theinsert 14 and the retainer 12, the retainer 12 pressing outwardlyagainst the receiver 10. Because the insert 14 is a lock and releaseinsert, the insert 14 is now wedged against the receiver at the surface95 and the polyaxial mechanism of the bone screw assembly 1 is nowlocked, even if the closure top 18 or 18″ is loosened and rotated awayfrom the sleeve surface 340.

A tensioning tool (not shown) known in the art may then be used to pullupon and put tension on the cord 306. It is noted that if more than onegripping closure tops 18″ are used at either end of a connector, one topwould be locked initially and then the other or others would be lockedafter tensioning, or alternatively perform more than one tensioningstep. Preferably a bumper 314 and end blocker 310 are used at at leastone end and the cord 306 is preferably tensioned until the bumper 314compresses and then the set screw 312 is rotated and driven into theblocker 310 and up against the cord 306 using a driving tool (not shown)engaged with an inner drive of the screw 312. The blocker 310advantageously includes opposed grooves 311 (or planar sides in someembodiments) allowing for the placement of a counter-torque tool forholding the blocker during tensioning and fixing of the cord 306 withinthe blocker. As explained in U.S. patent application Ser. No.12/802,849, the set screw 312 and blocker 310 combination preferablyincludes a limited travel feature such that the set screw is locked intoplace at a location that firmly holds but does not damage the cord 306.The cord 306 is ultimately trimmed to a desired length close to each endof the connector.

The connector assembly is thus substantially dynamically loaded andoriented relative to the cooperating vertebra, providing relief (e.g.,shock absorption) and protected movement with respect to flexion,extension, distraction and compressive forces placed on the assembly andthe connected bone screws 1. In some embodiments of a connecting memberaccording to the invention, a sleeve and rod combination may be used atone end (or both ends) of the assembly to provide a hard, non-elasticelongate portion for attachment to an additional bone screw or screws,if needed, to provide a connecting member with both dynamic, elasticsegments as well as a longer rigid inelastic segment.

Eventually, if the spine requires more rigid support, such a connectingmember assembly may be removed and replaced with another longitudinalconnecting member, such as a solid rod or bar, having the same width ordiameter as body portions of the sleeves 304, utilizing the samereceivers 10 and the same or similar closure structures 18.Alternatively, if less support is eventually required, a less rigid,more flexible assembly, for example, an assembly having spacers 316 anda bumper or bumpers 314 made of a softer more compressible material thanthe spacer and bumper being replaced thereby, also utilizing the samebone screws 1 and the closures 18″ as well as the closure 18.

With reference to FIGS. 63-74, the alternative sleeve 305 is illustratedwith the bone screw assembly 1, both the slip 18 and grip 18″ closuretops, and also with alternative spacers 316′. The sleeve 305 issubstantially similar to the sleeve 304 with the exception that insteadof having flanges with a partially circular profile defined by thepartially cylindrical surfaces 346 and the planar surfaces 348, thesleeve 305 has opposed flanges 438 that are substantially rectangular inprofile. Specifically, the sleeve flanges 438 have top planar surfaces446, opposed planar front and back surfaces 447 and outer planar endsurfaces 448 for abutting against the spacers 316 or 316′ and the bumper314. Otherwise, the sleeve 305 includes a body 434, a through bore 436,a body top 440, a body cylindrical bottom surface 441, body lower planarsurfaces 442, protruding portions 444, flange bottom surfaces 450,curved transition surfaces 451, a transition flanged surface 452, inneropposed facing surfaces 453, concave or cupped surfaces 455 upper innercylindrical surfaces 456 and a transverse bore 460 that are the same orsimilar in form and function to the respective body 334, through bore336, body top 340, body cylindrical bottom surface 341, body lowerplanar surfaces 342, protruding portions 344, flange bottom surfaces350, curved transition surfaces 351, transition flanged surface 352,inner opposed facing surfaces 353, concave or cupped surfaces 355 upperinner cylindrical surfaces 356 and the transverse bore 360 of the insert304 as previously described herein. The substantially rectangularflanges 438 provide for a low profile sleeve having the top surface 446conveniently located for cooperation with certain spacers to providetorsion control, such as the spacer 316′ shown in FIGS. 71-74. Thespacer 316′ is elliptical or oval in profile, having a curved outersurface 490 having compression grooves 491 formed therein, a centralbore 492, opposed planar end surfaces 494 and an upper overhangingportion or lip, generally 496 located at a narrowing of the ellipse, thelip 496 further having a planar end surface 497 and a planar bottomsurface or ledge 498. As shown in FIGS. 71 and 72, the ledge surface 498is sized and shaped to engage the top surface 446 of the sleeve flange438 with the lip end surface 497 adjacent to the receiver 10 armsurfaces, providing some torsion control to the overall assembly. Thenarrow profile of the spacer 316′ improves the low profile nature of theresulting assembly and also provides improved stability in flexion andextension. It is noted that during a surgical procedure, the spacers316′ must be cut to a desired length by the surgical staff, at a sideopposite the compression grooves 491, similar to what is discussed abovewith respect to the spacers 316. To do this, a special jig (not shown)is used to cut the spacer in such a way as to include an overhanging lip469 on the freshly cut side thereof.

With reference to FIGS. 75-106, the reference number 1001 generallyrepresents an alternative polyaxial bone screw apparatus or assemblyaccording to the present invention. The assembly 1001 includes a shank1004; a receiver 1010; a friction fit retainer 1012, and a crown-likecompression or pressure insert 1014. There are many similarities betweenthe assembly 1001 and the assembly 1. Differences between theembodiments 1 and 1001 mainly concern the retainer 1012 that is made bya turning process, allowing for more radiused surfaces that provideimproved friction fit between inner tangs and the shank head 1008, forexample. Ridges or other high friction coefficient treatments on theoutside tangs provide improved gripping with the receiver during certainstages of assembly. Furthermore, as will be described in greater detailbelow, the retainer 1012 includes another lower outer tier or skirtcooperating with the receiver that allows for an even lower profile,dropping the retainer (and thus the cooperating shank head) even lowerin the receiver than what is shown in FIG. 1 for the assembly 1. As withthe assembly 1, the receiver 1010, retainer 1012 and compression insert1014 are initially assembled and may be further assembled with the shank1004 either prior or subsequent to implantation of the shank body 1006into a vertebra 17, similar to the assembly 1 previously describedherein and also as will be described in greater detail below. FIGS. 75and 99, for example, further show a closure structure 1018 for capturinga longitudinal connecting member, for example, a rod 1021 which in turnengages the compression insert 1014 that presses against the shank head1008 into fixed frictional contact with the retainer 1012, so as tocapture, and fix the longitudinal connecting member 1021 within thereceiver 1010 and thus fix the member 1021 relative to the vertebra 17.Substantially similar to the assembly 1 previously described herein, thereceiver 1010 and the shank 1004 cooperate in such a manner that thereceiver 1010 and the shank 1004 can be secured at any of a plurality ofangles, articulations or rotational alignments relative to one anotherand within a selected range of angles both from side to side and fromfront to rear, to enable flexible or articulated engagement of thereceiver 1010 with the shank 1004 until both are locked or fixedrelative to each other near the end of an implantation procedure. Theillustrated closure top 1018 and the rod 1021 are the same orsubstantially similar in form and function to the respective closure top18 and rod 21 previously described herein with respect to the assembly1, and thus shall not be re-described in this section.

The shank 1004 is also substantially similar in form, function andmaterials to the shank 4 previously described herein. Thus, the shank1004 has a body 1006, a head 1008, a shank thread 1024, a neck 1026, atip 1028, a shank body top 1032 where the thread 1024 terminates, a headspherical surface 1034, a head top edge 1038, a head upperfrusto-conical surface 1039, an internal drive 1046 and a cannulationbore 1050 (not shown) the same or substantially similar to therespective shank body 6, head 8, shank thread 24, neck 26, tip 28, shankbody top 32, head spherical surface 34, head top edge 38, head upperfrusto-conical surface 39, internal drive 46 and bore 50 previouslydescribed herein with respect to the shank 4 of the assembly 1. Similarto the head hemisphere 40 of the shank 4, the illustrated shank head1008 has a hemisphere location illustrated by a dotted line 1040.

With particular reference to FIGS. 75-79, the receiver 1010 is alsosubstantially similar in form, function and materials to the receiver 10previously described herein. However, there are a few differencesbetween the receiver 10 and the receiver 1010 including spaced apertures1056 extending through a base 1060 of the receiver 1010 and somegeometry changes with respect to other apertures and inner surfacesdefining a cavity, generally 1061, of the receiver 1010 which will bedescribed in greater detail below. First, with respect to thesimilarities between the two receivers, the receiver 1010 includes outercurved surfaces 1058 and outer planar surfaces 1059 of the receiver base1060, opposed arms 1062, inset surfaces 1063 between the arms 1062, aU-shaped channel 1064 having an upper opening 1066 and a seat 1068, arminner planar surfaces 1069 on either side of a generally cylindricalinner arm surface, generally 1070, a guide and advancement structure1072, arm top surfaces 1073, outer circular apertures 1074, outercylindrical arm surfaces 1076, opposed through apertures 1077, opposedholding tabs 1078, tab sloping outer surfaces 1080 and 1081, tab topsurfaces 1082, tab insert engaging surfaces 1084, tab lower surfaces1085, tab inner lower sloping surfaces 1086, tab inner cylindricalsurfaces 1087, tab side surfaces 1088, top surfaces 1089 of theapertures 1077, side surfaces 1090 of the apertures 1077 and U-shapedbottom surfaces 1091 of the apertures 1077, that are the same orsubstantially similar to respective outer curved surfaces 58 and outerplanar surfaces 59 of the receiver base 60, opposed arms 62, insetsurfaces 63 between the arms 62, the U-shaped channel 64 having theupper opening 66 and seat 68, arm inner planar surfaces 69, cylindricalinner arm surfaces, generally 70, guide and advancement structure 72,arm top surfaces 73, outer circular apertures 74, outer cylindrical armsurfaces 76, opposed through apertures 77, opposed holding tabs 78, tabsloping outer surfaces 80 and 81, tab top surfaces 82, tab insertengaging surfaces 84, tab lower surfaces 85, tab inner lower slopingsurfaces 86, tab inner cylindrical surfaces 87, tab side surfaces 88,top surfaces 89 defining the apertures 77, side surfaces 90 defining theapertures 77 and U-shaped bottom surfaces 91 defining the apertures 1077previously described herein with respect to the receiver 10. However,the U-shaped bottom surfaces 1091 are disposed lower within the receiver1010 than the bottom surfaces 91 of the receiver 10. The U-shaped bottomsurfaces 1091 are generally aligned with and spaced from the throughapertures 1056, each of the curved bottom surfaces 1091 and the lowersurfaces defining the apertures 1056 being approximately the samedistance from a receiver bottom surface 1108, allowing for receipttherethrough of tooling (not shown) used to evenly and equally pressinwardly on outer tangs of the retainer 1012 during assembly of theretainer with the other bone screw components as will be described ingreater detail below.

With further reference to the receiver inner cavity 1061 that issubstantially similar, but not identical to the cavity 61 of thereceiver 10, there are arm inner cylindrical surfaces 1092 locateddirectly under the guide and advancement structure 1072, similar to thesurface 92 located under the guide and advancement structure 72 of thereceiver 10. The receiver 1010 also has a radially inwardly locatedinner cylindrical surface 1095 that is similar to the surface 95 of thereceiver 10. Like the surface 95, the surface 1095 is sized and shapedfor a locking interference fit with the insert 1015. Like the surface95, the surface 1095 defines an upper portion of the receiver base 1060and also is adjacent to a chamber ceiling surface 1096. However, thereceiver 10 surface 92 is located next to the surface 95, whereas in thereceiver 1010, other cylindrical surfaces that vary slightly in diameterfrom one another are located between the surface 1095 and the surface1092, namely, they are cylindrical surfaces 1093 and 1094. The steppedsurface 1094′ is the same or similar to the surface 94 of the receiver10. Unlike the receiver 10, the upper surface 1096 defining the receiverchamber or cavity extends outwardly radially to a cylindrical surface1098. The receiver 1010 does not include an equivalent to the receiversurface 97. A remainder of the receiver cavity 1061 is substantiallysimilar to the cavity 61, the receiver cavity 1061 being defined by theexpansion chamber surface 1098 and surfaces defining a seat for theretainer 1012, including cylindrical surfaces 1100 and 1101, annularseats 1102 and 1103, a transition stepped surface 1104, a circular rimor edge 1106, a frusto-conical surface 1107, a base bottom surface 1108and a lower opening 1110, the same or similar in form and function tothe respective cylindrical surface 98, surfaces defining the seat forthe retainer 12, including cylindrical surfaces 100 and 101, annularseats 102 and 103, transition stepped surface 104, circular rim or edge106, frusto-conical or flared surface 107, base bottom surface 108 andthe lower opening 110 of the receiver 10 previously described herein.

With particular reference to FIGS. 75 and 80-86, the lower open or splitfriction fit retainer 1012, that operates to capture the shank upperportion 1008 within the receiver 1010 is shown. In certain stages ofassembly and operation, the retainer 1012 is partially constrainedwithin the receiver, being captured within the receiver cavity 1061 at alocation below the surface 1096, the retainer 1012 being rotatable withrespect to the receiver, but not pivotable thereto and not readilyremovable out of the receiver once deployed downward into the receivercavity 1061. The retainer 1012 has a central axis that is operationallythe same as a central axis associated with the receiver 1010 when theshank upper portion 1008 and the retainer 1012 are installed within thereceiver 1010. The retainer 1012 includes a body 1115 having an outersurface 1116, upstanding inner panels or tangs 1117 and upstanding outerpanels 1118 that are similar, but not identical in form and function tothe respective retainer body 115 with outer surface 116, inner 117 andouter 118 panels previously described herein with respect to theassembly 1. As compared to the retainer 12, the retainer 1012 outer bodysurface 1116 is an outer cylinder broken only by a retainer slit 1148.Furthermore, the inner and outer retainer tangs are formed in a mannerdifferently from that of the retainer 112 (a machining turning or spunprocess), providing for more radiused surfaces. There are three innerpanels 117 and six outer panels 118. However, it is foreseen that theremay be fewer or greater numbers of inner and outer panels.

Like the retainer 12 lower skirt 121, the retainer 1012 includes a lowerouter cylindrical skirt or surface 1121 that is located beneath thepanels 1118. The retainer 1012 further includes an additional lower orbottom skirt 1121′ that is frusto-conical in form and extends downwardlyand radially inwardly to a bottom surface 1122. The retainer 1012 alsoincludes inner panel outer surfaces 1128, inner panel radiused surfaces1129, inner panel top surfaces 1130, outer panel surfaces 1132, outerpanel inner surfaces 1133 and outer panel top surfaces 1134 that aresubstantially similar in form and function to the respective inner panelouter surfaces 128, inner panel radiused surfaces 129, inner panel topsurfaces 130, outer panel outer surfaces 132, outer panel inner surfaces133 and outer panel top surfaces 134 previously described herein withrespect to the retainer 12. With particular reference to FIG. 81, theretainer 1012 further includes ridges 1135 located on the panel outersurfaces 1132 for temporary frictional engagement with the receiversurface 1095 during assembly as will be described in greater detailbelow. It is foreseen that the ridges 1135 may be replaced with othertypes of surface treatment to provide an increased coefficient offriction between the retainer and the receiver, such as knurling orother roughening surface treatments.

The retainer 1012 has a central channel, generally 1141, an innerfrusto-conical surface 1143, an inner cylindrical surface 1145, an innerstepped surface 1146 having an edge 1147, a slit, generally 1148,curvate, cupped surfaces 1149 and first and second surfaces 1152 and1153 defining the slit 1148 that are the same or similar in form andfunction to the respective central channel 141, inner frusto-conicalsurface 143, inner cylindrical surface 145, inner stepped surface 146having an edge 147, the slit, generally 148, curvate, cupped surfaces149 and the first and second surfaces 152 and 153 defining the slit 148.Unlike the retainer 12, because of the lower skirt 1121′, the shankengagement edge 1147 and the cupped surfaces 1149 are located relativelylower within the inner shank final engagement and locking mechanism ofthe retainer 1012 than the edge 147 and cupped surfaces 149 of theretainer 12, providing for greater and improved polyaxial motion of theassembly.

Like the retainer 12, the retainer 1012 is made from a resilientmaterial, such as a stainless steel or titanium alloy, so that theretainer body 1115 may be expanded and the tabs or panels 1117 and 1118of the retainer may be manipulated during various steps of assembly aswill be described in greater detail below. The rotatability of thesemi-constrained retainer 1012 with respect to the receiver 1010 allowsfor manipulation and placement of the retainer with respect to the shankto result in an increased angle of articulation at a location desired bya surgeon.

With particular reference to FIGS. 75 and 87-89, the locking compressioninsert 1014 is illustrated that is sized and shaped to be received byand down-loaded into the receiver 1010 at the upper opening 1066. Thecompression insert 1014 is so substantially similar to the insert 14previously described herein that it will not be discussed further,except to identify the reference numerals that point to the variousfeatures. Thus, the insert 1014 includes a body 1156, arms 1157,cylindrical body surfaces 1158, interference fit surfaces 1159, armouter surfaces 1160, a lower cylindrical surface 1161 a sloping ledgetransition surface 1162, a planar bottom 1164, arm top surfaces 1165,through apertures 1167, shallow apertures 1168, grooves 1170, a throughbore 1171, a U-shaped channel or saddle 1173, a saddle seat 1174, aninner cylindrical surface 1176, a lower radiused surface 1178 and ashank gripping portion 1180 that are the same or substantially similarin form, function and materials to the respective body 156, arms 157,cylindrical body surfaces 158, interference fit surfaces 159, arm outersurfaces 160, lower cylindrical surface 161, sloping ledge transitionsurface 162, planar bottom 164, arm top surfaces 165, through apertures167, shallow apertures 168, grooves 170, through bore 171, saddle 173,saddle seat 174, inner cylindrical surface 176, lower radiused surface178 and shank gripping portion 180 of the insert 14 previously describedherein.

Pre-assembly of the receiver 1010, retainer 1012 and compression insert1014 is shown in FIGS. 90-94. With particular reference to FIG. 90,first the retainer 1012 is inserted into the upper receiver opening1066, leading with the outer panels 1118 with the panel 1118 topsurfaces 1134 facing one arm 1062 and the retainer bottom surface 1122facing the opposing arm 1062. The retainer 1012 is then lowered in suchsideways manner into the channel 1064 and partially into the receivercavity 1061, followed by tilting the retainer 1012 such that at leastone panel top surface 1134 is located beneath the surface 1085 of one ofthe receiver holding tabs 1078 and the opposed holding tab 1078 islocated generally between a pair of panels 1118, for example, at or nearthe retainer slit 1148 as shown in FIG. 91. Then, with further referenceto FIG. 91, the retainer 1012 is tilted into a position wherein thecentral axis of the retainer 1012 is generally aligned with the receivercentral axis and the receiver holding tabs 1078 are each located betweenpairs of adjacent panels 1118 and extend over retainer body top surfaces1126 located opposite one another, with each tab surface 1085 beinglocated directly above a top surface 1126 or the slit 1148. FIG. 91 alsoillustrates the retainer 1012 at a compressed state with the slitsurfaces 1152 and 1153 being at a near touching state so that theretainer cylindrical surface slides past the receiver inner surface1095.

With reference to FIG. 92, after the panels 1118 are located betweenholding tabs 1078, the retainer 1012 is lowered into the receiver cavity1061 with the resilient panels 1118 being pressed inwardly, usingtooling, or by the use of a downward force that results in compressionof the panels 1118 toward the receiver central axis. With reference toFIG. 93, the retainer 1012 is pressed past the receiver surfaces 1095and allowed to “deploy”, the tangs 1118 expanding to a neutral or nearneutral state after dropping into the cavity defined primarily by thecylindrical surface 1098, the outer tangs 1118 located beneath thesurface 1096, capturing the retainer 1012 within the receiver cavity1061. With reference to FIGS. 93 and 94, at this time the insert 1014 isdropped into the receiver channel 1064 and then rotated into place in amanner the same as described previously herein with respect to theinsert 14 and the receiver 10. Tools (not shown) are then insertedthrough the receiver apertures 1056 and above the U-shaped surfaces 1091of the apertures 1077 to press inwardly on the retainer tangs 1118 asshown in FIG. 94 and then the retainer 1012 is moved upwardly within thecavity 1061 as shown in FIG. 95. The tooling is released and theretainer tang outer surfaces having the ridges 1135 abut against thereceiver surfaces 1095 and are frictionally engaged therewith. Theretainer 1012 is now captured between the surfaces 1095 and located at adesired space in the receiver 1010 for both shipping and for furtherassembly with the shank 1004. The insert 1014 is also fully capturedwithin the receiver 1010 by the guide and advancement structure 1072prohibiting movement of the insert 1014 up and out through the receiveropening 1066 as well as by retainer 1012 located below the insert.

With reference to FIG. 95, the pre-assembled receiver, insert andretainer are placed above the shank upper portion 1008 until the shankupper portion is received within the opening 1110. With particularreference to FIGS. 95-98, as the shank upper portion 1008 is moved intothe interior 1061 of the receiver base, the shank upper portion 1008presses upwardly against the retainer 1012 in the receiver recesspartially defined by the cylindrical surface 1098. As the shank head1008 continues to move upwardly toward the channel 1064, the shank headsurface 1034 forces the retainer 1012 against the insert 1014. However,the insert 1014 is prohibited from moving upward by the receiver guideand advancement structure 1072. Therefore, the upwardly moving shankhead 1008 forces a widening of the retainer slit 1148 and correspondingoutward movement of the body 1115 of the retainer 1012 towards thereceiver cylindrical surfaces 1098, 1100 and 1101 defining the receiverexpansion recess or chamber as best shown in FIG. 96, while the retainertangs 1118 near the top surfaces 1134 thereof are generally maintainedin a location directly below the insert 1014 bottom surface 1164. Atthis time, the spherical surface 1034 of the head 1008 comes intocontact with the retainer inner cylindrical body 1145 and the edge 1147.With reference to FIG. 97, the retainer 1012 begins to return towards aneutral or nominal state as the center of the sphere of the shank head1008 passes beyond the retainer surface 1147. By the time the hemisphereof the spherical surface 1034 extends into a desired captured locationwithin the retainer central channel 1141, the shank surface 1034 is incontact with the edge 1147 as well as with the inner panels 1117 atsurfaces 1129. The combination of the rim or edge 1147 surface contactand the panel 1117 surfaces 1129 contact resiliently pressing againstthe radiused surface 1034, provides a fairly tight friction fit betweenthe head 1008 and the retainer 1012, the surface 1034 being pivotablewith respect to the retainer 1012 with some force. Thus, a tight,non-floppy ball and socket joint is now created between the retainer1012 and the shank upper portion 1008.

With reference to FIG. 98, the receiver is then pulled upwardly or theshank 1004 and attached retainer 1012 are then moved manually downwardlyinto a position wherein the retainer panels 1118 are disengaged from thereceiver surfaces 1095, allowing the panels 1118 to resiliently releaseand extend outwardly into a neutral or near-neutral position at alocation below the receiver annular surface 1096 that defines theceiling of the receiver inner chamber 1061. The panels 1118 are nowcaptured within the receiver and the retainer with any upward movementresulting in the panel top surfaces 1134 abutting against the receiversurfaces 1096. However, although fully captured, the retainer/shankcombination is advantageously only partially restrained with respect tothe receiver, as a user is able to rotate the retainer 1012 about thereceiver 1010 central axis prior to locking of the shank 1004 withrespect to the receiver 1010. At this time also, the retainer is fullyseated on the receiver surfaces 1102 and 1103 and the surfaces 1116 and1121 are pressed outwardly into abutting relationship with the receiverwith the lower skirt 1121′ spaced from the receiver flared surface 1107and the retainer bottom surface 1122 in approximately the same plane asthe receiver bottom surface 1108. With reference to FIG. 100, downwardpressure of the shank head 1008 on the retainer edge 1147 furtherexpands the retainer body 1115 outwardly, the retainer body formed inpart by the lower skirt surfaces 1121 and 1121′ advantageously allowsfor the head 1008 to seat lower within the receiver than in other knownpolyaxial bone anchors as well as lower than that shown in the assembly1. The skirt feature thus allows for a more stable lower seating surfacein combination with the retainer cupped surface 1149 that allows forincreased angular orientation of the shank with respect to the retainer,and thus with respect to the entire bone screw assembly, such an angularincrease being possible without the need to provide a cut-out or cuppedsurface at and near the receiver bottom 1108. Also advantageous is thefact that the partially constrained retainer 1012 may be rotated withrespect to the receiver 1010 about the receiver central axis, allowingfor the user to choose the location of the increased angle oforientation between the receiver 1010 and the shank 1004.

With reference to FIG. 98, after the retainer 1012 is moved downwardlyinto the receiver 1010 and seated on the surfaces 1102 and 1103, theinsert 1014 remains located spaced above the shank head 1008 as thereceiver spring tabs 1078 and/or the receiver stepped surface 1094prohibits downward movement of the insert 1014 unless a downward forceis applied on the insert either by a tool or the rod 1021 and closuretop 1018 shown in FIG. 99, for example and discussed previously hereinwith respect to the almost identical locking insert 1014. At this time,prior to locking with a closure top, the receiver 1010 may bearticulated to a desired angular position with respect to the shank 4(such as the angular orientations shown in FIGS. 101 and 102, forexample), that will be held, but not locked, by the frictionalengagement between the retainer 1012 inner panels 1117 and the shankupper portion 1008. As discussed above with respect to the assembly 1,at this time, the lock and release insert 1014 may be pressed intointerference fit relationship with the receiver surfaces 1095 by a toolor by the closure top 1018 pressing down upon the rod 1021 that in turnpresses down upon the insert 1014 as shown in FIGS. 99 and 100. Theassembly 1001 may be outfitted with a deformable rod and cooperatingclosure as previously described herein with respect to the assembly 1.The insert 1014 may also be unlocked as described above with respect tothe assembly 1.

With reference to FIGS. 101-103, different angular or articulatedpositions of the shank 1004 with respect to the receiver 1010 are shown,some making full use of the slit 1148 and adjacent cut-out or cuppedsurfaces 1149 of the retainer 1112. For example, in FIG. 102, the shank1008 is pivoted toward and into engagement with the cupped surfaces 1149(about thirty degree articulation) as compared to the arrangement shownin FIG. 101, wherein the shank 1004 is pivoted in a direction oppositeto the retainer slit 1148 and the surfaces 1149 (about twenty degreearticulation).

FIG. 103 illustrates an alternative receiver 1010′ that includes abottom surface 1108′ further defined by a pair of opposed, stepped andconcave curved bottom surfaces 1109′. Otherwise, the receiver 1010′ isidentical to the receiver 1010 described above and thus fully cooperateswith the retainer 1012, insert 1014, shank 1004, rod 1021 and closuretop 1018 in a manner substantially identical to what has been describedabove with respect to the assembly 1001. FIG. 103 shows the retainer1012 mounted in the receiver 1010′ with the retainer slit 1148 andsurfaces 1149 aligned with one of the stepped surfaces 1109′, suchalignment providing for at least a forty degree angle of articulationbetween the shank 1004 and the receiver 1010′.

With reference to FIGS. 104-106, an alternative non-locking compressioninsert 1014′ is illustrated for use with the shank 1004, receiver 1010,retainer 1012, closure top 1018 and rod 1021 previously describedherein. The insert 1014′ is substantially similar to the non-lockinginsert 214 previously described herein. During assembly with thereceiver, the insert 1014′ is rotated and the receiver holding tabsurfaces 1084 slide along grooves 1070′ until they spring into theapertures 1066′ having bars 1067′ that are the same or similar to theapertures and bars 267 previously described herein with respect to theinsert 214. The bars 1067′ hold the non-locking insert 1014′ in placeabove the retainer 1012 until placed into locking engagement with theshank head 1008 by pressure from the rod 1021 and closure top 1018.

With reference to FIGS. 107-137, the reference number 2001 generallyrepresents another alternative polyaxial bone screw apparatus orassembly according to the present invention. The assembly 2001 includesa shank 2004; a receiver 2010; a friction fit retainer 2012, and acrown-like compression or pressure insert 2014. There are manysimilarities between the assembly 2001 and the assemblies 1 and 1001.However, the assembly 2001 differs from the assembly 1001 and theassembly 1 in how the retainer 2012 is deployed within the receiver 2010which also changes how the shank 2004 is “popped” into the mechanism asa whole. These differences mainly concern the sizing of certain receiver2010 surfaces with respect to the retainer 2012 so as to provide anabutment surface for the retainer that results in a subsequentinterference fit between the retainer 2012 and the receiver 2010. Also,ridges or other high friction coefficient treatments on a head 2008 ofthe shank 2004 provide for gripping between the shank 2004 the retainer2012 during certain assembly steps. Like the retainer 1012, the retainer2012 includes an additional lower outer tier or skirt cooperating withthe receiver 2010 that allows for a low profile, similar to the assembly1001, previously described herein. FIGS. 107, 130 and 131, for example,further show a closure structure 2018 for capturing a longitudinalconnecting member, for example, a rod 2021 which in turn engages thecompression insert 2014 that presses against the shank head 2008 intofixed frictional contact with the retainer 2012, so as to capture, andfix the longitudinal connecting member 2021 within the receiver 2010 andthus fix the member 2021 relative to the vertebra 17. Substantiallysimilar to the assemblies 1 and 1001 previously described herein, thereceiver 2010 and the shank 2004 cooperate in such a manner that thereceiver 2010 and the shank 2004 can be secured at any of a plurality ofangles, articulations or rotational alignments relative to one anotherand within a selected range of angles both from side to side and fromfront to rear, to enable flexible or articulated engagement of thereceiver 2010 with the shank 2004 until both are locked or fixedrelative to each other near the end of an implantation procedure. Theillustrated closure top 2018 and the rod 2021 are the same orsubstantially similar in form and function to the respective closure top18 and rod 21 previously described herein with respect to the assembly1, and thus shall not be re-described in this section. Furthermore, FIG.132 illustrates an alternative deformable rod 2021′ and cooperatingclosure top 2018′ that are identical or substantially similar to therespective deformable rod 21′ and closure top 18′ previously describedherein.

The shank 2004 is substantially similar in form, function and materialsto the shank 4 previously described herein. Thus, the shank 2004 has abody 2006, a head 2008, a shank thread 2024, a neck 2026, a tip 2028, ashank body top 2032 where the thread 2024 terminates, a head sphericalsurface 2034, a head top edge 2038, a head upper frusto-conical surface2039, an internal drive 2046 and a cannulation bore 2050 the same orsubstantially similar to the respective shank body 6, head 8, shankthread 24, neck 26, tip 28, shank body top 32, head spherical surface34, head top edge 38, head upper frusto-conical surface 39, internaldrive 46 and bore 50 previously described herein with respect to theshank 4 of the assembly 1. Furthermore, at a location directly beneath ahemisphere of the head 2008, the shank surface 2034 includes a pluralityof parallel ridges 2035, running about the head 2008 and parallel to theplane of the circular shank top edge 2038. The ridges 2035 aid theretainer in gripping the shank head 2008 during certain assembly stepsas shown, for example, in FIGS. 127 and 128 and described in greaterdetail below.

With particular reference to FIGS. 109-111, the receiver 2010 issubstantially similar in form, function and materials to the receivers1010 and 10 previously described herein. However, there are a fewdifferences between the receiver 2010 and the receiver 1010 as thereceiver 2010 does not include the spaced apertures 1056, but otherwiseincludes seating surfaces described in greater detail below that providea stop for holding the retainer 2012 in a desired position duringcertain assembly steps and a later interference type fit between theretainer 2012 and the receiver 2010. First, with respect to thesimilarities between the receivers, the receiver 2010 includes outercurved surfaces 2058 and outer planar surfaces 2059 of the receiver base2060, opposed arms 2062, inset surfaces 2063 between the arms 2062, aU-shaped channel 2064 having an upper opening 2066 and a seat 2068, arminner planar surfaces 2069 on either side of a generally cylindricalinner arm surface, generally 2070, a guide and advancement structure2072, arm top surfaces 2073, outer circular apertures 2074, outercylindrical arm surfaces 2076, opposed through apertures 2077, opposedholding tabs 2078, tab sloping outer surfaces 2080 and 2081, tab topsurfaces 2082, tab insert engaging surfaces 2084, tab lower surfaces2085, tab inner lower sloping surfaces 2086, tab inner cylindricalsurfaces 2087, tab side surfaces 2088, top surfaces 2089 of theapertures 2077, side surfaces 2090 of the apertures 2077 and U-shapedbottom surfaces 2091 of the apertures 2077, that are the same orsubstantially similar to respective outer curved surfaces 58 and outerplanar surfaces 59 of the receiver base 60, opposed arms 62, insetsurfaces 63 between the arms 62, the U-shaped channel 64 having theupper opening 66 and seat 68, arm inner planar surfaces 69, cylindricalinner arm surfaces, generally 70, guide and advancement structure 72,arm top surfaces 73, outer circular apertures 74, outer cylindrical armsurfaces 76, opposed through apertures 77, opposed holding tabs 78, tabsloping outer surfaces 80 and 81, tab top surfaces 82, tab insertengaging surfaces 84, tab lower surfaces 85, tab inner lower slopingsurfaces 86, tab inner cylindrical surfaces 87, tab side surfaces 88,top surfaces 89 defining the apertures 77, side surfaces 90 defining theapertures 77 and U-shaped bottom surfaces 91 defining the apertures 1077previously described herein with respect to the receiver 10.

With further reference to the receiver inner arm surfaces, generally2070 and the cavity 2061, such surface features are substantiallysimilar to the inner arm surface 1070 and the surfaces defining thecavity 1061 of the receiver 1010 of the assembly 1001, but notcompletely identical thereto. So, with respect to the similarities, thereceiver 2010 includes inner arm surfaces 2092, 2093 and 2094 and stepsurfaces 2094′ that are the same in form and function to the respectivearms surfaces 1092, 1093, 1094 and step surface 1094′ previouslydescribed herein with respect to the receiver 1010. Also, with respectto the surfaces defining the receiver cavity 2061, the receiver 2010includes a cylindrical surface 2095, a chamber ceiling surface 2096, acylindrical expansion chamber surface 2098 that are the same orsubstantially similar in form and function to the respective cylindricalsurface 1095, chamber ceiling surface 1096 and cylindrical surface 1098of the receiver 1010.

With regard to surfaces that define the retainer final seating portionof the chamber 2061, the receiver 2010 includes a lower cylindricalsurface 2101, annular seating surfaces 2102 and 2103, a lower edge 2106,a flared surface 2107, a base bottom surface 2108 and a lower opening2110 that are the same or substantially similar to the respective lowercylindrical surface 1101, annular seating surfaces 1102 and 1103, loweredge 1106, flared or frusto-conical surface 1107, base bottom surface1108 and lower opening 1110 of the receiver 1010. With particularreference to FIG. 111, although somewhat similar the cylindrical surface1101, the receiver 2010 surface that is located between the annularsurface 2102 and a transition step 2104 differs from the surface 1104.The transition step 2104 also varies slightly from the transition step1104 of the receiver 1010. In the receiver 2010, the beveled transitionstep 2104 extends further radially inwardly than the step 1104,providing a step edge 2105 and adjacent beveled or sloped surface 2105′that acts as a stop for the retainer 2012 (see FIG. 122) unless anduntil the retainer 2012 is forced into a close fit engagement with theedge 2105, force being required to move the retainer 2012 beyond theedge 2105 as shown in FIGS. 128 and 129 and as will be discussed ingreater detail below. The surface 2100, rather than being parallel to acentral axis of the receiver 2010, is angled slightly outwardly towardsthe receiver base surface 2058. Thus, unlike the receiver 1010 in whichthe surface 1100 is perpendicular to the surface 1102, in the receiver2010, the surface 2100 is at an acute angle with respect to the surface2102, albeit, only slightly less than ninety degrees. This slight slopeof the surface 2100 allows for some clearance and ease in when movingthe retainer 2012 past the edge 2105 and then down into abutment withthe annular seating surfaces 2102 and 2103.

With particular reference to FIGS. 107 and 112-116, the lower open orsplit friction fit retainer 2012, that operates to capture the shankupper portion 2008 within the receiver 2010 is shown. Unlike theretainers 12 and 1012, in all stages of assembly with the shank 2004,and in subsequent operation, the retainer 2012 is partially constrainedwithin the receiver, being captured within the receiver cavity 2061 at alocation below the surface 2096, the retainer 1012 being rotatable withrespect to the receiver, but not pivotable thereto and not readilyremovable out of the receiver once deployed downward into the receivercavity 2061. The retainer 2012 has a central axis that is operationallythe same as a central axis associated with the receiver 2010 when theshank upper portion 2008 and the retainer 2012 are installed within thereceiver 2010. The retainer 2012 includes a body 2115 having an outercylindrical surface 2116, upstanding inner panels or tangs 2117 andupstanding outer panels 2118 that are substantially similar to therespective body 1115, outer surface 1116, inner tangs 1117 and outertangs 1118 previously described herein with respect to the assembly1001. However, the outer tangs 2118 do not include outer ridges or othersurface treatment because the retainer 2012 tangs 2118 are notcompressed inwardly by the receiver during shipping or assembly with theshank 2008. The inner tangs 2117 also differ slightly from the tangs1117 in that an inner radiused surface 2129 does not have quite as muchsurface area as the inner surface 1129. The sizing of the surface 2129roughly corresponds to the sizing of the shank ridges 2035, providingoptimal gripping between the shank head 2008 and the radiused surface2129 for a desirable friction fit during manipulation of the shank 2004with respect to the receiver 2010 prior to locking of the polyaxialmechanism of the assembly 2001. As with the retainer 1012, the retainer2012 includes three inner panels 2117 and six outer panels 2118.However, it is foreseen that there may be fewer or greater numbers ofinner and outer panels.

The retainer 2012 includes a cylindrical lower skirt 2121, afrusto-conical bottom skirt 2121′ and a bottom surface 2122 that aresubstantially the same or similar to the respective skirt features 1121and 1121′ and bottom surface 1122 previously discussed herein withrespect to the retainer 1012. Between the outer cylindrical surface 2116and the skirt 2121 is a linking substantially planar annular surface2124. Between the skirt 2121 and the bottom skirt 2121′ is a linkingsubstantially planar annular surface 2125. It is the surface 2124 thatabuts against the receiver edge 2105 during certain assembly steps asshown, for example, in FIG. 122.

Other features of the retainer 2012 include tang 2117 outer surfaces2128, inner radiused surfaces 2129, top surfaces 2130, tang 2118 outersurfaces 2132, inner surfaces 2133 and top surfaces 2134 that aresimilar to the respective retainer 1012 tang 1117 outer surfaces 1128,inner radiused surfaces 1129, top surfaces 1130, tang 1118 outersurfaces 1132, inner surfaces 1133 and top surfaces 1134. As statedabove, the inner tang radiused surfaces 2129 do differ from the tangsurfaces 1129 with respect to surface area, but otherwise similarlyfunction to provide for friction fit during manipulation of the shankwith respect to the retainer. The retainer 2012 further includes acentral channel 2141, an inner frusto-conical surface 2143, an innercylindrical surface 2145, a step surface 2146 and inner shank grippingedge 2147, a slit 2148, cupped or cut-out surfaces 2149 and surfaces2152 and 2153 defining the slit 2148 that are the same or substantiallysimilar to the respective central channel 1141, inner frusto-conicalsurface 1143, inner cylindrical surface 1145, step surface 1146 andinner shank gripping edge 1147, slit 1148, cupped or cut-out surfaces1149 and surfaces 1152 and 1153 defining the slit 1148 of the retainer1012 previously described herein.

With particular reference to FIGS. 107 and 117-118, the lockingcompression insert 2014 is illustrated that is sized and shaped to bereceived by and down-loaded into the receiver 2010 at the upper opening2066. The compression insert 2014 is so substantially similar to theinserts 14 and 1014 previously described herein that it will not bediscussed further, except to identify the reference numerals that pointto the various features. Thus, the insert 2014 includes a body 2156,arms 2157, cylindrical body surfaces 2158, interference fit surfaces2159, arm outer surfaces 2160, a lower cylindrical surface 2161 asloping ledge transition surface 2162, a planar bottom 2164, arm topsurfaces 2165, through apertures 2167, shallow apertures 2168, grooves2170, a through bore 2171, a U-shaped channel or saddle 2173, a saddleseat 2174, an inner cylindrical surface 2176, a lower radiused surface2178 and a shank gripping portion 2180 that are the same orsubstantially similar in form, function and materials to the respectivebody 156, arms 157, cylindrical body surfaces 158, interference fitsurfaces 159, arm outer surfaces 160, lower cylindrical surface 161,sloping ledge transition surface 162, planar bottom 164, arm topsurfaces 165, through apertures 167, shallow apertures 168, grooves 170,through bore 171, saddle 173, saddle seat 174, inner cylindrical surface176, lower radiused surface 178 and shank gripping portion 180 of theinsert 14 previously described herein.

Pre-assembly of the receiver 2010, retainer 2012 and compression insert2014 is shown in FIGS. 119-124. With particular reference to FIG. 119,first the retainer 2012 is inserted into the upper receiver opening2066, leading with the outer panels 2118 with the panel 2118 topsurfaces 2134 facing one arm 2062 and the retainer bottom surface 2122facing the opposing arm 2062. The retainer 2012 is then lowered in suchsideways manner into the channel 2064 and partially into the receivercavity 2061, followed by tilting the retainer 2012 such that at leastone panel top surface 2134 is located beneath the surface 2085 of one ofthe receiver holding tabs 2078 and the opposed holding tab 2078 islocated generally between a pair of panels 2118, for example, at or nearthe retainer slit 2148 as shown in FIG. 120. Then, the retainer 2012 istilted into a position wherein the central axis of the retainer 2012 isgenerally aligned with the receiver central axis and the receiverholding tabs 2078 are each located between pairs of adjacent panels 2118and extend over retainer body top surfaces 2126 located opposite oneanother, with each tab surface 2085 being located directly above a topsurface 2126 or the slit 2148. FIG. 120 also illustrates the retainer2012 at a compressed state with the slit 2148 surfaces 2152 and 2153being at a near touching state so that the retainer cylindrical surfaceslides past the receiver inner surface 2095.

After the panels 2118 are located between holding tabs 2078, theretainer 2012 is lowered into the receiver cavity 2061 with theresilient panels 2118 being pressed inwardly, using tooling, or by theuse of a downward force that results in compression of the panels 2118toward the receiver central axis. With reference to FIG. 121, theretainer 2012 is pressed past the receiver surfaces 2095 and allowed to“deploy”, the tangs 2118 expanding after dropping into the cavitydefined primarily by the cylindrical surface 2098, the outer tangs 2118located beneath the surface 2096, capturing the retainer 2012 within thereceiver cavity 2061. With reference to FIG. 122, at this time also, theretainer 2012 is prohibited from moving into a fully seated positionwithin the lower portion of the receiver cavity 2061. The Edge 2105 andadjacent surface 2105′ provide an abutment stop with the retainerannular surface 2124 being temporarily seated thereupon. Downward forceis required to move the retainer 2012 into a fully seating position withthe receiver surfaces 2102 and 2103. Therefore, the retainer isadvantageously prohibited at this time from moving down past the edge2105 or moving up past the surface 2096 because of the outwarddeployment of the tangs 2118. With reference to FIG. 123, at this timethe insert 2014 is dropped into the receiver channel 2064 and thenrotated into place (see FIG. 124) in a manner the same as describedpreviously herein with respect to the insert 14 and the receiver 10.Now, the insert 1014 is also fully captured within the receiver 2010 bythe guide and advancement structure 2072 prohibiting movement of theinsert 1014 up and out through the receiver opening 2066 as well as bycaptured retainer 2012 located below the insert.

With further reference to FIG. 124, the pre-assembled receiver, insertand retainer are ready for shipping and also ready for attachment to theshank 2004. Such pre-assembly is placed above the shank upper portion2008 until the shank upper portion is received within the opening 2110.With particular reference to FIGS. 125-128, as the shank upper portion2008 is moved into the interior 2061 of the receiver base, the shankupper portion 2008 presses upwardly against the retainer 2012 in thereceiver recess partially defined by the cylindrical surface 2098, aswell as the cylindrical surfaces 2100 and 2101 as best shown in FIG. 125(showing maximum expansion). The retainer 2012 is blocked from furtherupper movement by the outer tangs 2118 abutting against the ceilingsurface 2096. With reference to FIG. 126, as the shank head 2008continues to move upwardly toward the channel 2064, the shank headsurface 2034 eventually abuts up against the insert 2014. However, theinsert 1014 is prohibited from moving upward by the receiver guide andadvancement structure 2072. Also with reference to FIG. 126 as well asFIG. 127, at this time, the shank head spherical surface 2034 at theridges 2035 comes into gripping contact with the radiused surfaces 2129of the retainer inner tangs 2117 and the retainer 2012 begins to returntowards a neutral or nominal state as the center of the sphere of theshank head 2008 has passed beyond the retainer surface 2147. Withreference to FIG. 128, the shank 2004 is shown in an initial stage ofpull down, with the radiused surfaces 2129 fairly tightly grippingagainst the ridged surface portion 2035. With reference to FIG. 129,further pulling of the shank 2004 downwardly away from the receiver2010, pulls the retainer 2116 past the receiver abutment edge 2105 andthe retainer is then placed in a fully seated position with the retainersurfaces 2124 and 2125 fully abutting against and seating on thereceiver surfaces 2102 and 2103. The radiused surfaces 2129 are still infrictional contact with the ridged surfaces 2035, providing a fairlytight friction fit between the head 2008 and the retainer 2012, thesurface 2034 being pivotable with respect to the retainer 2012 with someforce. Thus, a tight, non-floppy ball and socket joint is now createdbetween the retainer 2012 and the shank upper portion 2008. Althoughstill fully captured within the receiver, the outer tangs or panels 2118are still only partially restrained with respect to the receiver, as auser is able to rotate the retainer about the receiver central axisprior to locking of the shank with respect to the receiver. Thus, atthis time also, the retainer is fully seated on the receiver surfaces2102 and 2103 and the surfaces 2116 and 2121 are pressed outwardly intoabutting relationship with the receiver with the lower skirt 2121′spaced from the receiver flared surface 2107 and the retainer bottomsurface 2122 in approximately the same plane as the receiver bottomsurface 2108. With reference to FIG. 130, downward pressure of the shankhead 2008 on the retainer edge 2147 further expands the retainer body2115 outwardly, the retainer body formed in part by the lower skirtsurfaces 2121 and 2121′ advantageously allows for the head 2008 to seatlower within the receiver than in other known polyaxial bone anchors aswell as lower than that shown in the assembly 1. The skirt feature 2121and 2121′ thus allows for a more stable lower seating surface incombination with the retainer cupped surface 2149 that allows forincreased angular orientation of the shank with respect to the retainer,and thus with respect to the entire bone screw assembly, such an angularincrease being possible without the need to provide a cut-out or cuppedsurface at and near the receiver bottom 2108. Also advantageous is thefact that the partially constrained retainer 2012 may be rotated withrespect to the receiver 2010 about the receiver central axis, allowingfor the user to choose the location of the increased angle oforientation between the receiver 2010 and the shank 2004.

With reference to FIG. 130, after the retainer 2012 is moved downwardlyinto the receiver 2010 and seated on the surfaces 2102 and 2103, theinsert 2014 remains located spaced above the shank head 2008 as thereceiver spring tabs 2078 and/or the receiver stepped surface 2094prohibits downward movement of the insert 2014 unless a downward forceis applied on the insert either by a tool or the rod 2021 and closuretop 2018 shown in FIG. 130, for example and discussed previously hereinwith respect to the almost identical locking insert 14. At this time,prior to locking with a closure top, the receiver 2010 may bearticulated to a desired angular position with respect to the shank 2004(such as the angular orientations shown in FIGS. 133 and 134, forexample), that will be held, but not locked, by the frictionalengagement between the retainer 2012 inner panels 2117 and the shankupper portion 2008. As discussed above with respect to the assembly 1,at this time, the lock and release insert 2014 may be pressed intointerference fit relationship with the receiver surfaces 2095 by a toolor by the closure top 2018 pressing down upon the rod 2021 that in turnpresses down upon the insert 2014 as shown in FIG. 130. With referenceto FIGS. 131 and 132, the closure top 2018 and the rod 2021 may beloosened or removed and the assembly 2001 may be outfitted with thedeformable rod 2921′ and cooperating closure top 2018′ without unlockingthe polyaxial mechanism, as previously described herein with respect tothe assembly 1. The insert 2014 may also be unlocked, if desired, asdescribed above with respect to the assembly 1.

With reference to FIGS. 133-134, different angular or articulatedpositions of the shank 2004 with respect to the receiver 2010 are shown,some making full use of the slit 2148 and adjacent cut-out or cuppedsurfaces 2149 of the retainer 2112. For example, in FIG. 134, the shank2008 is pivoted toward and into engagement with the cupped surfaces 2149(about thirty degree articulation) as compared to the arrangement shownin FIG. 133, wherein the shank 2004 is pivoted in a direction oppositeto the retainer slit 2148 and the surfaces 2149 (about twenty degreearticulation). An alternative receiver similar to the receiver 1010′previously described herein may also be used with the other componentsof the assembly 2001 to provide for additional degrees of angulararticulation.

With reference to FIGS. 135-137, an alternative non-locking compressioninsert 2014′ is illustrated for use with the shank 2004, receiver 2010,retainer 2012, closure top 2018 and rod 2021 previously describedherein. The insert 2014′ is substantially similar to the non-lockinginsert 214 previously described herein. During assembly with thereceiver, the insert 2014′ is rotated and the receiver holding tabsurfaces 2084 slide along grooves 2070′ until they spring into theapertures 2066′ having bars 2067′ that are the same or similar to theapertures and bars 267 previously described herein with respect to theinsert 214. The bars 2067′ holding the non-locking insert 2014′ in placeabove the retainer 2012 until placed into locking engagement with theshank head 1008 by pressure from the rod 2021 and closure top 2018. Itis noted that because of how the retainer 2012 is initially capturedwithin the receiver cavity 2061, the bars 2067′ may not be necessary, asa slight dropping of the insert 2014′ would not cause accidental andunwanted early deployment of the retainer 2012 (as could possibly happenwith the retainer 1012) as the retainer 2012 is already “deployed”,i.e., the tangs 2118 are already in a neutral position within thereceiver chamber during all of the assembly steps with both the insert2014 and the shank 2004.

It is to be understood that while certain forms of the present inventionhave been illustrated and described herein, it is not to be limited tothe specific forms or arrangement of parts described and shown.

What is claimed and desired to be secured by Letters Patent is asfollows:
 1. In a bone anchor, the improvement comprising: a) a shankhaving a body for fixation to a bone and an integral upper portionhaving a convex substantially spherical first surface with a firstradius; b) a receiver having a base and a pair of upright arms formingan open channel, the base defining a chamber and having a lower opening,the channel communicating with the chamber; and c) a resilient openretainer captured within the chamber and expandable about at least aportion of the shank upper portion, the retainer having a body and anupwardly extending super-structure, the body partially defining an inneredge and the super-structure defining a plurality of surfaces providinga friction fit between the retainer and the shank during non-lockingangular manipulation of the shank with respect to the receiver and theinner edge frictionally engaging the shank first spherical surfaceduring final locking of the shank with respect to the receiver with theretainer being in expansion-only locking engagement with both the shankupper portion and the receiver.
 2. The improvement of claim 1 furthercomprising an insert within the receiver, the insert having a lowersurface in final locking engagement with the shank upper portion.
 3. Theimprovement of claim 1 wherein the retainer superstructure includes aplurality of upwardly extending inner tangs, each tang having an innerradiused surface in frictional engagement with the shank duringnon-locking angular manipulation of the shank with respect to thereceiver.
 4. The improvement of claim 3 wherein the retainersuperstructure further includes a plurality of resilient upwardly andoutwardly extending outer tangs and the retainer body has a base with atleast a first planar surface and the receiver has a second planarsurface partially defining the receiver chamber and wherein prior toinsertion of the shank upper portion into the receiver base, the outertangs engage an upper surface defining the receiver chamber andresiliently hold the retainer in an upper portion of the receiverchamber and wherein after the shank upper portion is received throughthe retainer base and the retainer base first planar surface is seatedon the receiver second surface, the resilient outer tangs expand to aneutral state and are captured within the receiver chamber.
 5. Theimprovement of claim 4 wherein the retainer outer tangs have of surfacetreatment to provide an increased coefficient of friction between theretainer and the receiver upper surface.
 6. The improvement of claim 1further comprising an insert within the receiver, the insert having alower surface in final locking engagement with the shank upper portionand an outer structure and wherein the receiver includes inwardlyprojecting resilient tabs in temporary contact with the insert outerstructure to hold the insert during assembly of the shank upper portionand the retainer within the receiver chamber to prohibit the insert frompushing the retainer into early deployment within a lower portion of thereceiver chamber prior to the shank and retainer being fully assembledand seated near the receiver lower opening.
 7. The improvement of claim1 wherein the retainer body has a base with at least a first planarsurface and substructure located below the first planar surface, thesubstructure also located near the inner edge and supporting the shankupper portion during manipulation of and final locking of the shank withrespect to the receiver, the receiver having a second planar surfacepartially defining the receiver chamber and located near the loweropening and wherein the first planar surface is seated on the secondplanar surface during final locking.
 8. The improvement of claim 1wherein the shank upper portion has a surface treatment to provide anincreased coefficient of friction between the shank upper portion andthe retainer plurality of surfaces during non-locking angularmanipulation of the shank with respect to the receiver.
 9. Theimprovement of claim 8 wherein the surface treatment is a plurality ofridges.
 10. In a bone anchor, the improvement comprising: a) a shankhaving a body for fixation to a bone and an integral upper portionhaving a curved surface; b) a receiver having a base and a pair ofupright arms forming an open channel, the base defining a chamber andhaving a lower opening, the channel communicating with the chamber, thebase further defined by a stepped feature adjacent the lower opening,the stepped feature having a first planar surface and a substantiallycylindrical surface substantially perpendicular to the first planarsurface; and c) a resilient open retainer captured within the chamberand expandable about at least a portion of the shank upper portion, theretainer having a body with an outer surface and a base, the base havinga second planar surface, the retainer further having a lower skirtextending below the base second planar surface and inwardly of the outersurface of the body, the retainer base having an inner edge locatedabove and near the lower skirt, the inner edge frictionally engaging theshank upper portion curved surface during final locking of the shankwith respect to the receiver with the retainer being in expansion-onlylocking engagement with both the shank upper portion and the receiverand the retainer second planar surface being in engagement with thereceiver stepped feature.
 11. The improvement of claim 10 wherein thereceiver stepped feature has more than one planar surface.
 12. Theimprovement of claim 11 wherein the open retainer further comprises asub-skirt disposed below the lower skirt, the sub-skirt having an outerfrusto-conical surface.
 13. The improvement of claim 10 furthercomprising an insert within the receiver, the insert having a lowersurface in final locking engagement with the shank upper portion curvedsurface.
 14. The improvement of claim 10 wherein the retainer furthercomprises an upwardly extending super-structure having at least twosurfaces providing a friction fit between the retainer and the shankduring non-locking angular manipulation of the shank with respect to thereceiver.
 15. The improvement of claim 14 wherein the shank upperportion curved surface is substantially spherical and the retainersuper-structure comprises a plurality of radiused surfaces in frictionfit engagement with the shank upper portion curved surface duringnon-locking angular manipulation of the shank with respect to thereceiver.
 16. The improvement of claim 15 wherein the retainersuperstructure further includes a plurality of resilient upwardly andoutwardly extending outer tangs, the outer tangs engaging an uppersurface defining the receiver chamber and resiliently holding theretainer in an upper portion of the receiver chamber prior to and duringloading of the shank into the receiver, the outer tangs expanding to aneutral state and captured within the receiver chamber prior to finallocking of the shank with respect to the receiver.
 17. The improvementof claim 10 wherein the retainer comprises a lower concave surface sizedand shaped to receive a portion of the shank to provide an extendedangle of pivot of the shank.
 18. The improvement of claim 17 wherein theretainer lower concave surface is located at a gap between surfaces ofthe retainer.
 19. In a bone anchor, the improvement comprising: a) ashank having a body for fixation to a bone and an integral upper portionhaving a first radiused surface; b) a receiver having a top portion anda base, the receiver top portion defining an open channel, the basedefining a cavity with an upper expansion portion and a lower portioncommunicating with a bottom opening, the channel communicating with thecavity, the base having a first planar surface partially defining thecavity lower portion and located near the bottom opening; c) at leastone insert disposed within the receiver, the insert having a secondradiused surface for final locking engagement with the first radiusedsurface; and d) a resilient open retainer captured within the cavity andexpandable about at least a portion of the shank in the upper expansionportion of the receiver cavity, the retainer having a body with an inneredge and a sub-structure extending below the body, the body having asecond planar surface located adjacent the sub-structure, the secondplanar surface located below the inner edge and seated on the receiverfirst planar surface during locking of the shank with respect to thereceiver wherein an expansion locking engagement occurs between theshank upper portion and the retainer inner edge and between the retainerand the receiver.
 20. The improvement of claim 19 wherein the insert hasa surface sized and shaped for locking interference fit with thereceiver.